[K/JS] Add support of compilation with ES-classes

build-common/test/org/jetbrains/kotlin/library/metadata/DebugKlibMetadataProtoBuf.java

@@ -65,7 +65,7 @@ public final class DebugKlibMetadataProtoBuf {
      * <code>optional int32 flags = 2;</code>
      *
      * <pre>
-     *0x1 = preRelease
+     *Possible values are listed in KlibMetadataHeaderFlags class.
      * </pre>
      */
     boolean hasFlags();
@@ -73,7 +73,7 @@ public final class DebugKlibMetadataProtoBuf {
      * <code>optional int32 flags = 2;</code>
      *
      * <pre>
-     *0x1 = preRelease
+     *Possible values are listed in KlibMetadataHeaderFlags class.
      * </pre>
      */
     int getFlags();
@@ -433,7 +433,7 @@ public final class DebugKlibMetadataProtoBuf {
      * <code>optional int32 flags = 2;</code>
      *
      * <pre>
-     *0x1 = preRelease
+     *Possible values are listed in KlibMetadataHeaderFlags class.
      * </pre>
      */
     public boolean hasFlags() {
@@ -443,7 +443,7 @@ public final class DebugKlibMetadataProtoBuf {
      * <code>optional int32 flags = 2;</code>
      *
      * <pre>
-     *0x1 = preRelease
+     *Possible values are listed in KlibMetadataHeaderFlags class.
      * </pre>
      */
     public int getFlags() {
@@ -1225,7 +1225,7 @@ public final class DebugKlibMetadataProtoBuf {
        * <code>optional int32 flags = 2;</code>
        *
        * <pre>
-       *0x1 = preRelease
+       *Possible values are listed in KlibMetadataHeaderFlags class.
        * </pre>
        */
       public boolean hasFlags() {
@@ -1235,7 +1235,7 @@ public final class DebugKlibMetadataProtoBuf {
        * <code>optional int32 flags = 2;</code>
        *
        * <pre>
-       *0x1 = preRelease
+       *Possible values are listed in KlibMetadataHeaderFlags class.
        * </pre>
        */
       public int getFlags() {
@@ -1245,7 +1245,7 @@ public final class DebugKlibMetadataProtoBuf {
        * <code>optional int32 flags = 2;</code>
        *
        * <pre>
-       *0x1 = preRelease
+       *Possible values are listed in KlibMetadataHeaderFlags class.
        * </pre>
        */
       public Builder setFlags(int value) {
@@ -1258,7 +1258,7 @@ public final class DebugKlibMetadataProtoBuf {
        * <code>optional int32 flags = 2;</code>
        *
        * <pre>
-       *0x1 = preRelease
+       *Possible values are listed in KlibMetadataHeaderFlags class.
        * </pre>
        */
       public Builder clearFlags() {

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JSCompilerArguments.kt

@@ -291,6 +291,17 @@ class K2JSCompilerArguments : CommonCompilerArguments() {
     )
     var strictImplicitExportType: Boolean by FreezableVar(false)
 
+    @GradleOption(
+        value = DefaultValue.BOOLEAN_FALSE_DEFAULT,
+        gradleInputType = GradleInputTypes.INPUT,
+        shouldGenerateDeprecatedKotlinOptions = true,
+    )
+    @Argument(
+        value = "-Xes-classes",
+        description = "Generated JavaScript will use ES2015 classes."
+    )
+    var useEsClasses: Boolean by FreezableVar(false)
+
     @GradleOption(
         value = DefaultValue.BOOLEAN_TRUE_DEFAULT,
         gradleInputType = GradleInputTypes.INPUT,

compiler/cli/cli-js/src/org/jetbrains/kotlin/cli/js/K2JsIrCompiler.kt

@@ -144,7 +144,8 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
                     arguments.irSafeExternalBooleanDiagnostic,
                     messageCollector
                 ),
-                granularity = arguments.granularity
+                granularity = arguments.granularity,
+                es6mode = arguments.useEsClasses
             )
         }
 
@@ -668,7 +669,14 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
                 compilerConfiguration = configurationJs,
                 irFactory = { IrFactoryImplForJsIC(WholeWorldStageController()) },
                 mainArguments = mainCallArguments,
-                compilerInterfaceFactory = { mainModule, cfg -> JsIrCompilerWithIC(mainModule, cfg, arguments.granularity) }
+                compilerInterfaceFactory = { mainModule, cfg ->
+                    JsIrCompilerWithIC(
+                        mainModule,
+                        cfg,
+                        arguments.granularity,
+                        es6mode = arguments.useEsClasses
+                    )
+                }
             )
 
             val artifacts = cacheUpdater.actualizeCaches()

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/ValueRemapper.kt

@@ -30,6 +30,6 @@ abstract class AbstractValueRemapper : IrElementTransformerVoid() {
     }
 }
 
-open class ValueRemapper(private val map: Map<IrValueSymbol, IrValueSymbol>) : AbstractValueRemapper() {
+open class ValueRemapper(protected open val map: Map<IrValueSymbol, IrValueSymbol>) : AbstractValueRemapper() {
     override fun remapValue(oldValue: IrValueSymbol): IrValueSymbol? = map[oldValue]
 }

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/InlineClassDeclarationLowering.kt

@@ -125,6 +125,13 @@ class InlineClassLowering(val context: CommonBackendContext) {
                                         return builder.irGet(initFunction.valueParameters.single())
                                     return expression
                                 }
+
+                                override fun visitSetValue(expression: IrSetValue): IrExpression {
+                                    expression.transformChildrenVoid()
+                                    if (expression.symbol == origParameterSymbol)
+                                        return builder.irSet(initFunction.valueParameters.single(), expression.value)
+                                    return expression
+                                }
                             })
                         }
                         +irReturn(unboxedInlineClassValue())

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIntrinsics.kt

@@ -152,11 +152,9 @@ class JsIntrinsics(private val irBuiltIns: IrBuiltIns, val context: JsIrBackendC
     val jsAnyToString = getInternalFunction("anyToString")
     val jsCompareTo = getInternalFunction("compareTo")
     val jsEquals = getInternalFunction("equals")
-    val jsConstruct = getInternalFunction("construct")
     val jsNewTarget = getInternalFunction("jsNewTarget")
     val jsEmptyObject = getInternalFunction("emptyObject")
     val jsOpenInitializerBox = getInternalFunction("openInitializerBox")
-    val es6DefaultType = getInternalFunction("DefaultType")
 
     val jsImul = getInternalFunction("imul")
 
@@ -167,6 +165,8 @@ class JsIntrinsics(private val irBuiltIns: IrBuiltIns, val context: JsIrBackendC
     val jsBooleanInExternalLog = getInternalFunction("booleanInExternalLog")
     val jsBooleanInExternalException = getInternalFunction("booleanInExternalException")
 
+    val jsNewAnonymousClass = getInternalFunction("jsNewAnonymousClass")
+
     // Coroutines
 
     val jsCoroutineContext
@@ -369,7 +369,10 @@ class JsIntrinsics(private val irBuiltIns: IrBuiltIns, val context: JsIrBackendC
 
     val jsPrototypeOfSymbol = getInternalFunction("protoOf")
     val jsDefinePropertySymbol = getInternalFunction("defineProp")
-    val jsObjectCreateSymbol = getInternalFunction("objectCreate") // Object.create
+    val jsObjectCreateSymbol = getInternalFunction("objectCreate")                 // Object.create(x)
+    val jsCreateThisSymbol = getInternalFunction("createThis")                     // Object.create(x.prototype)
+    val jsBoxApplySymbol = getInternalFunction("boxApply")
+    val jsCreateExternalThisSymbol = getInternalFunction("createExternalThis")
 
     // Helpers:
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt

@@ -29,6 +29,12 @@ private fun DeclarationContainerLoweringPass.runOnFilesPostfix(files: Iterable<I
 
 private fun ClassLoweringPass.runOnFilesPostfix(moduleFragment: IrModuleFragment) = moduleFragment.files.forEach { runOnFilePostfix(it) }
 
+private fun List<Lowering>.toCompilerPhase() =
+    map {
+        @Suppress("USELESS_CAST")
+        it.modulePhase as CompilerPhase<JsIrBackendContext, Iterable<IrModuleFragment>, Iterable<IrModuleFragment>>
+    }.reduce { acc, lowering -> acc.then(lowering) }
+
 private fun makeJsModulePhase(
     lowering: (JsIrBackendContext) -> FileLoweringPass,
     name: String,
@@ -683,19 +689,6 @@ private val typeOperatorLoweringPhase = makeBodyLoweringPhase(
     )
 )
 
-private val es6AddInternalParametersToConstructorPhase = makeBodyLoweringPhase(
-    ::ES6AddInternalParametersToConstructorPhase,
-    name = "ES6CreateInitFunctionPhase",
-    description = "Add `box` and `resultType` params, create init functions for constructors"
-)
-
-private val es6ConstructorLowering = makeBodyLoweringPhase(
-    ::ES6ConstructorLowering,
-    name = "ES6ConstructorLoweringPhase",
-    description = "Lower constructors",
-    prerequisite = setOf(es6AddInternalParametersToConstructorPhase)
-)
-
 private val secondaryConstructorLoweringPhase = makeDeclarationTransformerPhase(
     ::SecondaryConstructorLowering,
     name = "SecondaryConstructorLoweringPhase",
@@ -791,10 +784,31 @@ private val invokeStaticInitializersPhase = makeBodyLoweringPhase(
     prerequisite = setOf(objectDeclarationLoweringPhase)
 )
 
+private val es6AddBoxParameterToConstructorsLowering = makeDeclarationTransformerPhase(
+    ::ES6AddBoxParameterToConstructorsLowering,
+    name = "ES6AddBoxParameterToConstructorsLowering",
+    description = "Add box parameter to a constructor if needed",
+)
+
+private val es6ConstructorLowering = makeDeclarationTransformerPhase(
+    ::ES6ConstructorLowering,
+    name = "ES6ConstructorLowering",
+    description = "Lower constructors declarations to support ES classes",
+    prerequisite = setOf(es6AddBoxParameterToConstructorsLowering)
+)
+
+private val es6ConstructorUsageLowering = makeBodyLoweringPhase(
+    ::ES6ConstructorCallLowering,
+    name = "ES6ConstructorCallLowering",
+    description = "Lower constructor usages to support ES classes",
+    prerequisite = setOf(es6ConstructorLowering)
+)
+
 private val objectUsageLoweringPhase = makeBodyLoweringPhase(
     ::ObjectUsageLowering,
     name = "ObjectUsageLowering",
-    description = "Transform IrGetObjectValue into instance generator call"
+    description = "Transform IrGetObjectValue into instance generator call",
+    prerequisite = setOf(primaryConstructorLoweringPhase)
 )
 
 private val escapedIdentifiersLowering = makeBodyLoweringPhase(
@@ -809,7 +823,6 @@ private val implicitlyExportedDeclarationsMarkingLowering = makeDeclarationTrans
     description = "Add @JsImplicitExport annotation to declarations which are not exported but are used inside other exported declarations as a type"
 )
 
-
 private val cleanupLoweringPhase = makeBodyLoweringPhase(
     { CleanupLowering() },
     name = "CleanupLowering",
@@ -912,8 +925,6 @@ val loweringList = listOf<Lowering>(
     defaultParameterCleanerPhase,
     captureStackTraceInThrowablesPhase,
     throwableSuccessorsLoweringPhase,
-    es6AddInternalParametersToConstructorPhase,
-    es6ConstructorLowering,
     varargLoweringPhase,
     multipleCatchesLoweringPhase,
     errorExpressionLoweringPhase,
@@ -927,10 +938,13 @@ val loweringList = listOf<Lowering>(
     inlineClassDeclarationLoweringPhase,
     inlineClassUsageLoweringPhase,
     autoboxingTransformerPhase,
-    blockDecomposerLoweringPhase,
     objectDeclarationLoweringPhase,
+    blockDecomposerLoweringPhase,
     invokeStaticInitializersPhase,
     objectUsageLoweringPhase,
+    es6AddBoxParameterToConstructorsLowering,
+    es6ConstructorLowering,
+    es6ConstructorUsageLowering,
     callsLoweringPhase,
     escapedIdentifiersLowering,
     implicitlyExportedDeclarationsMarkingLowering,
@@ -947,10 +961,56 @@ val pirLowerings = loweringList.filter { it is DeclarationLowering || it is Body
 val jsPhases = SameTypeNamedCompilerPhase(
     name = "IrModuleLowering",
     description = "IR module lowering",
-    lower = loweringList.map {
-        @Suppress("USELESS_CAST")
-        it.modulePhase as CompilerPhase<JsIrBackendContext, Iterable<IrModuleFragment>, Iterable<IrModuleFragment>>
-    }.reduce { acc, lowering -> acc.then(lowering) },
+    lower = loweringList.toCompilerPhase(),
+    actions = setOf(defaultDumper.toMultiModuleAction(), validationAction.toMultiModuleAction()),
+    nlevels = 1
+)
+
+private val es6CollectConstructorsWhichNeedBoxParameterLowering = makeDeclarationTransformerPhase(
+    ::ES6CollectConstructorsWhichNeedBoxParameters,
+    name = "ES6CollectConstructorsWhichNeedBoxParameters",
+    description = "[Optimization] Collect all of the constructors which requires box parameter",
+)
+
+private val es6BoxParameterOptimization = makeBodyLoweringPhase(
+    ::ES6ConstructorBoxParameterOptimizationLowering,
+    name = "ES6ConstructorBoxParameterOptimizationLowering",
+    description = "[Optimization] Remove box parameter from the constructors which don't require box parameter",
+    prerequisite = setOf(es6CollectConstructorsWhichNeedBoxParameterLowering)
+)
+
+private val es6CollectPrimaryConstructorsWhichCouldBeOptimizedLowering = makeDeclarationTransformerPhase(
+    ::ES6CollectPrimaryConstructorsWhichCouldBeOptimizedLowering,
+    name = "ES6CollectPrimaryConstructorsWhichCouldBeOptimizedLowering",
+    description = "[Optimization] Collect all of the constructors which could be translated into a regular constructor",
+)
+
+private val es6PrimaryConstructorOptimizationLowering = makeDeclarationTransformerPhase(
+    ::ES6PrimaryConstructorOptimizationLowering,
+    name = "ES6PrimaryConstructorOptimizationLowering",
+    description = "[Optimization] Replace synthetically generated static fabric method with a plain old ES6 constructors whenever it's possible",
+    prerequisite = setOf(es6CollectPrimaryConstructorsWhichCouldBeOptimizedLowering)
+)
+
+private val es6PrimaryConstructorUsageOptimizationLowering = makeBodyLoweringPhase(
+    ::ES6PrimaryConstructorUsageOptimizationLowering,
+    name = "ES6PrimaryConstructorUsageOptimizationLowering",
+    description = "[Optimization] Replace usage of synthetically generated static fabric method with a plain old ES6 constructors whenever it's possible",
+    prerequisite = setOf(es6BoxParameterOptimization, es6PrimaryConstructorOptimizationLowering)
+)
+
+val optimizationLoweringList = listOf<Lowering>(
+    es6CollectConstructorsWhichNeedBoxParameterLowering,
+    es6CollectPrimaryConstructorsWhichCouldBeOptimizedLowering,
+    es6BoxParameterOptimization,
+    es6PrimaryConstructorOptimizationLowering,
+    es6PrimaryConstructorUsageOptimizationLowering,
+)
+
+val jsOptimizationPhases = SameTypeNamedCompilerPhase(
+    name = "IrModuleOptimizationLowering",
+    description = "IR module optimization lowering",
+    lower = optimizationLoweringList.toCompilerPhase(),
     actions = setOf(defaultDumper.toMultiModuleAction(), validationAction.toMultiModuleAction()),
     nlevels = 1
 )

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsMapping.kt

@@ -7,9 +7,13 @@ package org.jetbrains.kotlin.ir.backend.js
 
 import org.jetbrains.kotlin.backend.common.DefaultDelegateFactory
 import org.jetbrains.kotlin.backend.common.DefaultMapping
+import org.jetbrains.kotlin.ir.backend.js.utils.MutableReference
 import org.jetbrains.kotlin.ir.declarations.*
 
 class JsMapping : DefaultMapping() {
+    val esClassWhichNeedBoxParameters = mutableSetOf<IrClass>()
+    val esClassToPossibilityForOptimization = mutableMapOf<IrClass, MutableReference<Boolean>>()
+
     val outerThisFieldSymbols = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrClass, IrField>()
     val innerClassConstructors = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrConstructor, IrConstructor>()
     val originalInnerClassPrimaryConstructorByClass = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrClass, IrConstructor>()
@@ -20,8 +24,6 @@ class JsMapping : DefaultMapping() {
     val classToSyntheticPrimaryConstructor = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrClass, IrConstructor>()
     val privateMemberToCorrespondingStatic = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrFunction, IrSimpleFunction>()
 
-    val constructorToInitFunction = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrConstructor, IrSimpleFunction>()
-
     val enumEntryToGetInstanceFun = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrEnumEntry, IrSimpleFunction>()
     val enumEntryToInstanceField = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrEnumEntry, IrField>()
     val enumConstructorToNewConstructor = DefaultDelegateFactory.newDeclarationToDeclarationMapping<IrConstructor, IrConstructor>()

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/dce/JsUsefulDeclarationProcessor.kt

@@ -9,26 +9,35 @@ import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.JsStatementOrigins
 import org.jetbrains.kotlin.ir.backend.js.export.isExported
 import org.jetbrains.kotlin.ir.backend.js.lower.isBuiltInClass
+import org.jetbrains.kotlin.ir.backend.js.lower.isEs6ConstructorReplacement
 import org.jetbrains.kotlin.ir.backend.js.utils.*
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrFunctionAccessExpression
+import org.jetbrains.kotlin.ir.expressions.IrGetValue
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.js.config.JSConfigurationKeys
+import org.jetbrains.kotlin.serialization.js.ModuleKind
 
 internal class JsUsefulDeclarationProcessor(
     override val context: JsIrBackendContext,
     printReachabilityInfo: Boolean,
     removeUnusedAssociatedObjects: Boolean
 ) : UsefulDeclarationProcessor(printReachabilityInfo, removeUnusedAssociatedObjects) {
-
     private val equalsMethod = getMethodOfAny("equals")
     private val hashCodeMethod = getMethodOfAny("hashCode")
+    private val isEsModules = context.configuration[JSConfigurationKeys.MODULE_KIND] == ModuleKind.ES
 
     override val bodyVisitor: BodyVisitorBase = object : BodyVisitorBase() {
         override fun visitCall(expression: IrCall, data: IrDeclaration) {
             super.visitCall(expression, data)
+
+            if (expression.usePrototype(data)) {
+                context.intrinsics.jsPrototypeOfSymbol.owner.enqueue(expression.symbol.owner, "access to super type")
+            }
+
             when (expression.symbol) {
                 context.intrinsics.jsBoxIntrinsic -> {
                     val inlineClass = context.inlineClassesUtils.getInlinedClass(expression.getTypeArgument(0)!!)!!
@@ -68,6 +77,21 @@ internal class JsUsefulDeclarationProcessor(
                     constructedClasses += classToCreate
                 }
 
+                context.intrinsics.jsCreateThisSymbol -> {
+                    val jsClassOrThis = expression.getValueArgument(0)
+
+                    val classTypeToCreate = when (jsClassOrThis) {
+                        is IrCall -> jsClassOrThis.getTypeArgument(0)!!
+                        is IrGetValue -> jsClassOrThis.type
+                        else -> error("Unexpected first argument of createThis function call")
+                    }
+
+                    val classToCreate = classTypeToCreate.classifierOrFail.owner as IrClass
+
+                    classToCreate.enqueue(data, "intrinsic: jsCreateThis")
+                    constructedClasses += classToCreate
+                }
+
                 context.intrinsics.jsEquals -> {
                     equalsMethod.enqueue(data, "intrinsic: jsEquals")
                 }
@@ -86,26 +110,6 @@ internal class JsUsefulDeclarationProcessor(
                     }
                 }
 
-                context.intrinsics.jsConstruct -> {
-                    val callType = expression.getTypeArgument(0)!!
-                    val constructor = callType.getClass()!!.primaryConstructor
-                    constructor!!.enqueue(data, "ctor call from jsConstruct-intrinsic")
-                }
-
-                context.intrinsics.es6DefaultType -> {
-                    //same as jsClass
-                    val ref = expression.getTypeArgument(0)!!.classifierOrFail.owner as IrDeclaration
-                    ref.enqueue(data, "intrinsic: jsClass")
-                    referencedJsClasses += ref
-
-                    //Generate klass in `val currResultType = resultType || klass`
-                    val arg = expression.getTypeArgument(0)!!
-                    val klass = arg.getClass()
-                    if (klass != null) {
-                        constructedClasses.add(klass)
-                    }
-                }
-
                 context.intrinsics.jsInvokeSuspendSuperType,
                 context.intrinsics.jsInvokeSuspendSuperTypeWithReceiver,
                 context.intrinsics.jsInvokeSuspendSuperTypeWithReceiverAndParam -> {
@@ -137,48 +141,57 @@ internal class JsUsefulDeclarationProcessor(
                 }
         }
 
-        if (irClass.containsMetadata()) {
-            when {
-                irClass.isObject -> context.intrinsics.metadataObjectConstructorSymbol.owner.enqueue(irClass, "object metadata")
+        if (!irClass.containsMetadata()) return
 
-                irClass.isInterface -> {
-                    context.intrinsics.implementSymbol.owner.enqueue(irClass, "interface metadata")
-                    context.intrinsics.metadataInterfaceConstructorSymbol.owner.enqueue(irClass, "interface metadata")
-                }
+        when {
+            irClass.isObject -> context.intrinsics.metadataObjectConstructorSymbol.owner.enqueue(irClass, "object metadata")
 
-                else -> {
-                    context.intrinsics.metadataClassConstructorSymbol.owner.enqueue(irClass, "class metadata")
-                }
+            irClass.isInterface -> {
+                context.intrinsics.implementSymbol.owner.enqueue(irClass, "interface metadata")
+                context.intrinsics.metadataInterfaceConstructorSymbol.owner.enqueue(irClass, "interface metadata")
             }
+
+            else -> context.intrinsics.metadataClassConstructorSymbol.owner.enqueue(irClass, "class metadata")
         }
 
-        if (!irClass.isExpect && !irClass.isExternal && !irClass.defaultType.isAny()) {
-            if (!irClass.isInterface) {
-                context.intrinsics.jsPrototypeOfSymbol.owner.enqueue(irClass, "class metadata")
-            }
+        context.intrinsics.setMetadataForSymbol.owner.enqueue(irClass, "metadata")
 
-            if (irClass.superTypes.any { !it.isInterface() }) {
-                context.intrinsics.jsObjectCreateSymbol.owner.enqueue(irClass, "class metadata")
-            }
+        if (irClass.containsInterfaceDefaultImplementation()) {
+            context.intrinsics.jsPrototypeOfSymbol.owner.enqueue(irClass, "interface default implementation")
+        }
 
-            if (irClass.isInner || irClass.isObject) {
-                context.intrinsics.jsDefinePropertySymbol.owner.enqueue(irClass, "class metadata")
-            }
+        if ((!context.es6mode || !isEsModules) && (irClass.isInner || irClass.isObject)) {
+            context.intrinsics.jsDefinePropertySymbol.owner.enqueue(irClass, "object lazy initialization")
+        }
 
-            context.intrinsics.setMetadataForSymbol.owner.enqueue(irClass, "metadata")
+        if (context.es6mode) return
+
+        if (!irClass.isInterface) {
+            context.intrinsics.jsPrototypeOfSymbol.owner.enqueue(irClass, "class prototype access")
+        }
+
+        if (irClass.superTypes.any { !it.isInterface() }) {
+            context.intrinsics.jsObjectCreateSymbol.owner.enqueue(irClass, "class inheritance code")
         }
     }
 
     override fun processSimpleFunction(irFunction: IrSimpleFunction) {
         super.processSimpleFunction(irFunction)
 
+        if (irFunction.isEs6ConstructorReplacement) {
+            constructedClasses += irFunction.dispatchReceiverParameter?.type?.classOrNull?.owner!!
+        }
+
         if (irFunction.isReal && irFunction.body != null) {
             irFunction.parentClassOrNull?.takeIf { it.isInterface }?.enqueue(irFunction, "interface default method is used")
         }
 
+        if (context.es6mode && isEsModules) return
+
         val property = irFunction.correspondingPropertySymbol?.owner ?: return
 
-        if (property.isExported(context) || property.isOverriddenExternal()) {
+        if (property.isExported(context) || property.getJsName() != null || property.isOverriddenExternal()) {
+            context.intrinsics.jsPrototypeOfSymbol.owner.enqueue(irFunction, "property for export")
             context.intrinsics.jsDefinePropertySymbol.owner.enqueue(irFunction, "property for export")
         }
     }
@@ -225,8 +238,24 @@ internal class JsUsefulDeclarationProcessor(
     }
 
     override fun isExported(declaration: IrDeclaration): Boolean = declaration.isExported(context)
-}
 
+    private fun IrCall.usePrototype(container: IrDeclaration?): Boolean {
+        if (superQualifierSymbol == null) return false
+
+        val currentFun = (container as? IrSimpleFunction)
+        val currentClass = currentFun?.parentClassOrNull
+
+        return !context.es6mode ||
+                currentFun?.dispatchReceiverParameter == null ||
+                currentClass != null && (currentClass.isInner || currentClass.isLocal)
+    }
+
+    private fun IrClass.containsInterfaceDefaultImplementation(): Boolean {
+        return superTypes.any { it.classOrNull?.owner?.isExternal == true } ||
+                isExported(context) ||
+                isInterface && declarations.any { it is IrFunction && it.body != null }
+    }
+}
 
 private fun Collection<IrClass>.filterDescendantsOf(bases: Collection<IrClass>): Collection<IrClass> {
     val visited = hashSetOf<IrClass>()

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/dce/UsefulDeclarationProcessor.kt

@@ -12,7 +12,6 @@ import org.jetbrains.kotlin.ir.backend.js.utils.isAssociatedObjectAnnotatedAnnot
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
-import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.classifierOrNull
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/export/ExportModelGenerator.kt

@@ -13,8 +13,8 @@ import org.jetbrains.kotlin.descriptors.DescriptorVisibility
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
-import org.jetbrains.kotlin.ir.backend.js.lower.ES6AddInternalParametersToConstructorPhase.ES6_INIT_BOX_PARAMETER
-import org.jetbrains.kotlin.ir.backend.js.lower.ES6AddInternalParametersToConstructorPhase.ES6_RESULT_TYPE_PARAMETER
+import org.jetbrains.kotlin.ir.backend.js.lower.isBoxParameter
+import org.jetbrains.kotlin.ir.backend.js.lower.isEs6ConstructorReplacement
 import org.jetbrains.kotlin.ir.backend.js.utils.*
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
@@ -86,7 +86,7 @@ class ExportModelGenerator(val context: JsIrBackendContext, val generateNamespac
                     returnType = exportType(function.returnType),
                     typeParameters = function.typeParameters.map(::exportTypeParameter),
                     isMember = parent is IrClass,
-                    isStatic = function.isStaticMethodOfClass,
+                    isStatic = function.isStaticMethod,
                     isAbstract = parent is IrClass && !parent.isInterface && function.modality == Modality.ABSTRACT,
                     isProtected = function.visibility == DescriptorVisibilities.PROTECTED,
                     ir = function,
@@ -100,10 +100,9 @@ class ExportModelGenerator(val context: JsIrBackendContext, val generateNamespac
 
     private fun exportConstructor(constructor: IrConstructor): ExportedDeclaration? {
         if (!constructor.isPrimary) return null
-        val allValueParameters = listOfNotNull(constructor.extensionReceiverParameter) +
-                constructor.valueParameters.filterNot { it.origin === ES6_RESULT_TYPE_PARAMETER || it.origin === ES6_INIT_BOX_PARAMETER }
+        val allValueParameters = listOfNotNull(constructor.extensionReceiverParameter) + constructor.valueParameters
         return ExportedConstructor(
-            parameters = allValueParameters.map { exportParameter(it) },
+            parameters = allValueParameters.filterNot { it.isBoxParameter }.map { exportParameter(it) },
             visibility = constructor.visibility.toExportedVisibility()
         )
     }
@@ -696,6 +695,9 @@ private class ExportedClassDeclarationsInfo(
 private val IrClassifierSymbol.isInterface
     get() = (owner as? IrClass)?.isInterface == true
 
+private val IrFunction.isStaticMethod: Boolean
+    get() = isEs6ConstructorReplacement || isStaticMethodOfClass
+
 private fun getExportCandidate(declaration: IrDeclaration): IrDeclarationWithName? {
     // Only actual public declarations with name can be exported
     if (declaration !is IrDeclarationWithVisibility ||

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/export/ExportModelToJsStatements.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.ir.backend.js.export
 
 import org.jetbrains.kotlin.ir.backend.js.utils.*
 import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
+import org.jetbrains.kotlin.ir.backend.js.lower.isEs6ConstructorReplacement
 import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.JsAstUtils
 import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.defineProperty
 import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.jsAssignment
@@ -15,13 +16,16 @@ import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.jsElementAccess
 import org.jetbrains.kotlin.ir.backend.js.utils.Namer
 import org.jetbrains.kotlin.ir.backend.js.utils.emptyScope
 import org.jetbrains.kotlin.ir.backend.js.utils.getJsNameOrKotlinName
+import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.util.companionObject
+import org.jetbrains.kotlin.ir.util.isObject
 import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.util.collectionUtils.filterIsInstanceAnd
 
 class ExportModelToJsStatements(
-    private val namer: JsStaticContext,
-    private val declareNewNamespace: (String) -> String
+    private val staticContext: JsStaticContext,
+    private val es6mode: Boolean,
+    private val declareNewNamespace: (String) -> String,
 ) {
     private val namespaceToRefMap = mutableMapOf<String, JsNameRef>()
 
@@ -38,7 +42,8 @@ class ExportModelToJsStatements(
     fun generateDeclarationExport(
         declaration: ExportedDeclaration,
         namespace: JsExpression?,
-        esModules: Boolean
+        esModules: Boolean,
+        parentClass: IrClass? = null
     ): List<JsStatement> {
         return when (declaration) {
             is ExportedNamespace -> {
@@ -73,7 +78,7 @@ class ExportModelToJsStatements(
             }
 
             is ExportedFunction -> {
-                val name = namer.getNameForStaticDeclaration(declaration.ir)
+                val name = staticContext.getNameForStaticDeclaration(declaration.ir)
                 when {
                     namespace != null ->
                         listOf(jsAssignment(jsElementAccess(declaration.name, namespace), JsNameRef(name)).makeStmt())
@@ -88,28 +93,29 @@ class ExportModelToJsStatements(
 
             is ExportedProperty -> {
                 require(namespace != null || esModules) { "Only namespaced properties are allowed" }
-                val getter = declaration.irGetter?.let { namer.getNameForStaticDeclaration(it) }
-                val setter = declaration.irSetter?.let { namer.getNameForStaticDeclaration(it) }
-                if (namespace == null) {
-                    val property = JsVars.JsVar(
-                        JsName(declaration.name, false),
-                        JsObjectLiteral(false).apply {
-                            getter?.let {
-                                val fieldName = when (declaration.irGetter.origin) {
-                                    JsLoweredDeclarationOrigin.OBJECT_GET_INSTANCE_FUNCTION -> "getInstance"
-                                    else -> "get"
-                                }
-                                propertyInitializers += JsPropertyInitializer(JsStringLiteral(fieldName), it.makeRef())
-                            }
-                            setter?.let { propertyInitializers += JsPropertyInitializer(JsStringLiteral("set"), it.makeRef()) }
-                        }
-                    )
-                    listOf(
-                        JsVars(property),
-                        JsExport(property.name, JsName(declaration.name, false))
-                    )
-                } else {
-                    listOf(defineProperty(namespace, declaration.name, getter?.makeRef(), setter?.makeRef(), namer).makeStmt())
+                when {
+                    namespace == null -> {
+                        val property = declaration.generateTopLevelGetters()
+                        listOf(JsVars(property), JsExport(property.name, JsName(declaration.name, false)))
+                    }
+                    es6mode && declaration.isMember -> {
+                        val jsClass = parentClass?.getCorrespondingJsClass() ?: error("Expect to have parentClass at this point")
+                        jsClass.members += declaration.generateClassMembers()
+                        listOf(JsEmpty)
+                    }
+                    else -> {
+                        val getter = declaration.irGetter?.let { staticContext.getNameForStaticDeclaration(it) }
+                        val setter = declaration.irSetter?.let { staticContext.getNameForStaticDeclaration(it) }
+                        listOf(
+                            defineProperty(
+                                namespace,
+                                declaration.name,
+                                getter?.makeRef(),
+                                setter?.makeRef(),
+                                staticContext
+                            ).makeStmt()
+                        )
+                    }
                 }
             }
 
@@ -120,24 +126,31 @@ class ExportModelToJsStatements(
                 val newNameSpace = when {
                     namespace != null -> jsElementAccess(declaration.name, namespace)
                     else ->
-                        jsElementAccess(Namer.PROTOTYPE_NAME, namer.getNameForClass(declaration.ir).makeRef())
+                        jsElementAccess(Namer.PROTOTYPE_NAME, staticContext.getNameForClass(declaration.ir).makeRef())
                 }
-                val staticsExport = declaration.nestedClasses.flatMap { generateDeclarationExport(it, newNameSpace, esModules) }
+                val staticsExport =
+                    declaration.nestedClasses.flatMap { generateDeclarationExport(it, newNameSpace, esModules, declaration.ir) }
 
-                val objectExport = when (namespace) {
-                    null -> generateDeclarationExport(
-                        ExportedProperty(declaration.name, ExportedType.Primitive.Any, irGetter = declaration.irGetter),
+                val objectExport = when {
+                    es6mode || namespace == null -> generateDeclarationExport(
+                        ExportedProperty(
+                            declaration.name,
+                            ExportedType.Primitive.Any,
+                            isStatic = parentClass?.isObject != true,
+                            irGetter = declaration.irGetter,
+                            isMember = parentClass != null
+                        ),
                         namespace,
-                        esModules
+                        esModules,
+                        parentClass
                     )
-
                     else -> listOf(
                         defineProperty(
                             namespace,
                             declaration.name,
-                            namer.getNameForStaticDeclaration(declaration.irGetter).makeRef(),
+                            staticContext.getNameForStaticDeclaration(declaration.irGetter).makeRef(),
                             null,
-                            namer
+                            staticContext
                         ).makeStmt()
                     )
                 }
@@ -147,11 +160,11 @@ class ExportModelToJsStatements(
 
             is ExportedRegularClass -> {
                 if (declaration.isInterface) return emptyList()
-                val name = namer.getNameForStaticDeclaration(declaration.ir)
+                val name = staticContext.getNameForStaticDeclaration(declaration.ir)
                 val newNameSpace = when {
                     namespace != null -> jsElementAccess(declaration.name, namespace)
                     esModules -> name.makeRef()
-                    else -> prototypeOf(namer.getNameForClass(declaration.ir).makeRef(), namer)
+                    else -> prototypeOf(staticContext.getNameForClass(declaration.ir).makeRef(), staticContext)
                 }
                 val klassExport = when {
                     namespace != null -> jsAssignment(newNameSpace, JsNameRef(name)).makeStmt()
@@ -161,7 +174,7 @@ class ExportModelToJsStatements(
 
                 // These are only used when exporting secondary constructors annotated with @JsName
                 val staticFunctions = declaration.members
-                    .filter { it is ExportedFunction && it.isStatic }
+                    .filter { it is ExportedFunction && it.isStatic && !it.ir.isEs6ConstructorReplacement }
                     .takeIf { !declaration.ir.isInner }.orEmpty()
 
                 val enumEntries = declaration.members.filter { it is ExportedProperty && it.isStatic }
@@ -171,22 +184,75 @@ class ExportModelToJsStatements(
                     .map { it.generateInnerClassAssignment(declaration) }
 
                 val staticsExport = (staticFunctions + enumEntries + declaration.nestedClasses)
-                    .flatMap { generateDeclarationExport(it, newNameSpace, esModules) }
+                    .flatMap { generateDeclarationExport(it, newNameSpace, esModules, declaration.ir) }
 
                 listOfNotNull(klassExport) + staticsExport + innerClassesAssignments
             }
         }
     }
 
+    private fun ExportedProperty.generateTopLevelGetters(): JsVars.JsVar {
+        val getter = irGetter?.let { staticContext.getNameForStaticDeclaration(it) }
+        val setter = irSetter?.let { staticContext.getNameForStaticDeclaration(it) }
+
+        return JsVars.JsVar(
+            JsName(name, false),
+            JsObjectLiteral(false).apply {
+                getter?.let {
+                    val fieldName = when (irGetter?.origin) {
+                        JsLoweredDeclarationOrigin.OBJECT_GET_INSTANCE_FUNCTION -> "getInstance"
+                        else -> "get"
+                    }
+                    propertyInitializers += JsPropertyInitializer(JsStringLiteral(fieldName), it.makeRef())
+                }
+                setter?.let { propertyInitializers += JsPropertyInitializer(JsStringLiteral("set"), it.makeRef()) }
+            }
+        )
+    }
+
+    private fun ExportedProperty.generateClassMembers(): List<JsFunction> {
+        val getter = irGetter?.let { staticContext.getNameForStaticDeclaration(it) }
+        val setter = irSetter?.let { staticContext.getNameForStaticDeclaration(it) }
+
+        return buildList {
+            if (getter != null) {
+                add(JsFunction(emptyScope, "").also {
+                    it.name = JsName(name, false)
+                    if (isStatic) {
+                        it.modifiers.add(JsFunction.Modifier.STATIC)
+                    }
+                    it.modifiers.add(JsFunction.Modifier.GET)
+                    it.body = JsBlock().apply {
+                        statements.add(JsReturn(JsInvocation(getter.makeRef())))
+                    }
+                })
+            }
+            if (setter != null) {
+                add(JsFunction(emptyScope, "").also {
+                    val value = JsName("value", true)
+                    it.name = JsName(name, false)
+                    it.parameters.add(JsParameter(value))
+                    if (isStatic) {
+                        it.modifiers.add(JsFunction.Modifier.STATIC)
+                    }
+                    it.modifiers.add(JsFunction.Modifier.SET)
+                    it.body = JsBlock().apply {
+                        statements.add(JsExpressionStatement(JsInvocation(setter.makeRef(), value.makeRef())))
+                    }
+                })
+            }
+        }
+    }
+
     private fun ExportedClass.generateInnerClassAssignment(outerClass: ExportedClass): JsStatement {
-        val innerClassRef = namer.getNameForStaticDeclaration(ir).makeRef()
-        val outerClassRef = namer.getNameForStaticDeclaration(outerClass.ir).makeRef()
+        val innerClassRef = staticContext.getNameForStaticDeclaration(ir).makeRef()
+        val outerClassRef = staticContext.getNameForStaticDeclaration(outerClass.ir).makeRef()
         val companionObject = ir.companionObject()
         val secondaryConstructors = members.filterIsInstanceAnd<ExportedFunction> { it.isStatic }
         val bindConstructor = JsName("__bind_constructor_", false)
 
         val blockStatements = mutableListOf<JsStatement>(
-            JsVars(JsVars.JsVar(bindConstructor, innerClassRef.bindToThis()))
+            JsVars(JsVars.JsVar(bindConstructor, innerClassRef.bindToThis(innerClassRef)))
         )
 
         if (companionObject != null) {
@@ -200,35 +266,47 @@ class ExportModelToJsStatements(
         }
 
         secondaryConstructors.forEach {
-            val currentFunRef = namer.getNameForStaticDeclaration(it.ir).makeRef()
+            val currentFunRef = if (it.ir.isEs6ConstructorReplacement) {
+                JsNameRef(staticContext.getNameForMemberFunction(it.ir), innerClassRef)
+            } else {
+                staticContext.getNameForStaticDeclaration(it.ir).makeRef()
+            }
+
             val assignment = jsAssignment(
                 JsNameRef(it.name, bindConstructor.makeRef()),
-                currentFunRef.bindToThis()
+                currentFunRef.bindToThis(innerClassRef)
             ).makeStmt()
 
             blockStatements.add(assignment)
         }
 
         blockStatements.add(JsReturn(bindConstructor.makeRef()))
+        val innerClassGetter = JsFunction(emptyScope, JsBlock(*blockStatements.toTypedArray()), "inner class '$name' getter")
 
-        return defineProperty(
-            prototypeOf(outerClassRef, namer),
-            name,
-            JsFunction(
-                emptyScope,
-                JsBlock(*blockStatements.toTypedArray()),
-                "inner class '$name' getter"
-            ),
-            null,
-            namer
-        ).makeStmt()
+        return if (es6mode) {
+            outerClass.ir.getCorrespondingJsClass().members += innerClassGetter.also {
+                it.name = JsName(name, false)
+                it.modifiers.add(JsFunction.Modifier.GET)
+            }
+            JsEmpty
+        } else {
+            defineProperty(
+                prototypeOf(outerClassRef, staticContext),
+                name,
+                innerClassGetter,
+                null,
+                staticContext
+            ).makeStmt()
+        }
     }
 
-    private fun JsNameRef.bindToThis(): JsInvocation {
-        return JsInvocation(
-            JsNameRef("bind", this),
-            JsNullLiteral(),
-            JsThisRef()
-        )
+    private fun IrClass.getCorrespondingJsClass(): JsClass {
+        val jsClassModel = staticContext.classModels[symbol] ?: error("Class with name '$name' was not found")
+        return (jsClassModel.preDeclarationBlock.statements.first() as? JsExpressionStatement)?.expression as? JsClass
+            ?: error("Expect to have JsClass as a first statement inside JsIrClassModel")
+    }
+
+    private fun JsNameRef.bindToThis(bindTo: JsExpression): JsInvocation {
+        return JsInvocation(JsNameRef("bind", this), bindTo, JsThisRef())
     }
 }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/export/TransitiveExportCollector.kt

@@ -12,7 +12,6 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
-import org.jetbrains.kotlin.ir.types.impl.IrSimpleTypeImpl
 import org.jetbrains.kotlin.ir.backend.js.utils.isJsImplicitExport
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.superTypes

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/ic/CacheUpdater.kt

@@ -734,6 +734,7 @@ fun rebuildCacheForDirtyFiles(
     irFactory: IrFactory,
     exportedDeclarations: Set<FqName>,
     mainArguments: List<String>?,
+    es6mode: Boolean
 ): Pair<IrModuleFragment, List<Pair<IrFile, JsIrProgramFragment>>> {
     val emptyMetadata = object : KotlinSourceFileExports() {
         override val inverseDependencies = KotlinSourceFileMap<Set<IdSignature>>(emptyMap())
@@ -753,7 +754,13 @@ fun rebuildCacheForDirtyFiles(
         currentIrModule.files.filter { irFile -> irFile.fileEntry.name in files }
     } ?: currentIrModule.files
 
-    val compilerWithIC = JsIrCompilerWithIC(currentIrModule, configuration, JsGenerationGranularity.PER_MODULE, exportedDeclarations)
+    val compilerWithIC = JsIrCompilerWithIC(
+        currentIrModule,
+        configuration,
+        JsGenerationGranularity.PER_MODULE,
+        exportedDeclarations,
+        es6mode
+    )
 
     // Load declarations referenced during `context` initialization
     jsIrLinker.loadUnboundSymbols()

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/ir/IrBuilder.kt

@@ -15,19 +15,19 @@ import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
 import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.types.IrType
+import org.jetbrains.kotlin.ir.util.defaultType
 import org.jetbrains.kotlin.ir.util.parentAsClass
 import org.jetbrains.kotlin.name.Name
 
 object JsIrBuilder {
-
-
     object SYNTHESIZED_DECLARATION : IrDeclarationOriginImpl("SYNTHESIZED_DECLARATION")
 
     fun buildCall(
         target: IrSimpleFunctionSymbol,
         type: IrType? = null,
         typeArguments: List<IrType>? = null,
-        origin: IrStatementOrigin = JsStatementOrigins.SYNTHESIZED_STATEMENT
+        origin: IrStatementOrigin = JsStatementOrigins.SYNTHESIZED_STATEMENT,
+        superQualifierSymbol: IrClassSymbol? = null,
     ): IrCall {
         val owner = target.owner
         return IrCallImpl(
@@ -35,6 +35,7 @@ object JsIrBuilder {
             UNDEFINED_OFFSET,
             type ?: owner.returnType,
             target,
+            superQualifierSymbol = superQualifierSymbol,
             typeArgumentsCount = owner.typeParameters.size,
             valueArgumentsCount = owner.valueParameters.size,
             origin = origin
@@ -46,54 +47,95 @@ object JsIrBuilder {
         }
     }
 
-    fun buildConstructorCall(
-        target: IrConstructorSymbol,
-        type: IrType? = null,
-        typeArguments: List<IrType>? = null,
-        constructorTypeArguments: List<IrType>? = null,
-        origin: IrStatementOrigin = JsStatementOrigins.SYNTHESIZED_STATEMENT
-    ): IrConstructorCall {
+    fun buildArray(elements: List<IrExpression>, type: IrType, elementType: IrType): IrExpression {
+        return IrVarargImpl(
+            UNDEFINED_OFFSET,
+            UNDEFINED_OFFSET,
+            type,
+            elementType,
+            elements
+        )
+    }
+
+    fun buildDelegatingConstructorCall(target: IrConstructorSymbol, typeArguments: List<IrType?>? = null): IrDelegatingConstructorCall {
         val owner = target.owner
-        val parent = owner.parentAsClass
-        return IrConstructorCallImpl(
+        val irClass = owner.parentAsClass
+
+        return IrDelegatingConstructorCallImpl(
             UNDEFINED_OFFSET,
             UNDEFINED_OFFSET,
-            type ?: owner.returnType,
+            owner.returnType,
             target,
-            typeArgumentsCount = parent.typeParameters.size,
+            typeArgumentsCount = irClass.typeParameters.size,
             valueArgumentsCount = owner.valueParameters.size,
-            constructorTypeArgumentsCount = owner.typeParameters.size,
-            origin = origin
         ).apply {
             typeArguments?.let {
-                assert(typeArguments.size == typeArgumentsCount)
-                it.withIndex().forEach { (i, t) -> putTypeArgument(i, t) }
-            }
-            constructorTypeArguments?.let {
-                assert(constructorTypeArguments.size == constructorTypeArgumentsCount)
+                assert(it.size == typeArgumentsCount)
                 it.withIndex().forEach { (i, t) -> putTypeArgument(i, t) }
             }
         }
     }
 
+    fun buildConstructorCall(
+        target: IrConstructorSymbol,
+        typeArguments: List<IrType?>? = null,
+        constructorTypeArguments: List<IrType?>? = null,
+        origin: IrStatementOrigin = JsStatementOrigins.SYNTHESIZED_STATEMENT
+    ): IrConstructorCall {
+        val owner = target.owner
+        val irClass = owner.parentAsClass
+
+        return IrConstructorCallImpl(
+            UNDEFINED_OFFSET,
+            UNDEFINED_OFFSET,
+            owner.returnType,
+            target,
+            typeArgumentsCount = irClass.typeParameters.size,
+            constructorTypeArgumentsCount = owner.typeParameters.size,
+            valueArgumentsCount = owner.valueParameters.size,
+            origin = origin
+        ).apply {
+            typeArguments?.let {
+                assert(it.size == typeArgumentsCount)
+                it.withIndex().forEach { (i, t) -> putTypeArgument(i, t) }
+            }
+
+            constructorTypeArguments?.let {
+                assert(it.size == typeArgumentsCount)
+                it.withIndex().forEach { (i, t) -> putTypeArgument(i, t) }
+            }
+        }
+    }
+
+    fun buildRawReference(targetSymbol: IrFunctionSymbol, type: IrType): IrRawFunctionReference =
+        IrRawFunctionReferenceImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, type, targetSymbol)
+
     fun buildReturn(targetSymbol: IrFunctionSymbol, value: IrExpression, type: IrType) =
         IrReturnImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, type, targetSymbol, value)
 
     fun buildThrow(type: IrType, value: IrExpression) = IrThrowImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, type, value)
 
-    fun buildValueParameter(parent: IrFunction, name: String, index: Int, type: IrType): IrValueParameter =
+    fun buildValueParameter(
+        parent: IrFunction,
+        name: String,
+        index: Int,
+        type: IrType,
+        isAssignable: Boolean = false,
+        origin: IrDeclarationOrigin = SYNTHESIZED_DECLARATION
+    ): IrValueParameter =
         buildValueParameter(parent) {
-            this.origin = SYNTHESIZED_DECLARATION
+            this.origin = origin
             this.name = Name.identifier(name)
             this.index = index
             this.type = type
+            this.isAssignable = isAssignable
         }
 
     fun buildGetObjectValue(type: IrType, classSymbol: IrClassSymbol) =
         IrGetObjectValueImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, type, classSymbol)
 
-    fun buildGetValue(symbol: IrValueSymbol) =
-        IrGetValueImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, symbol.owner.type, symbol, JsStatementOrigins.SYNTHESIZED_STATEMENT)
+    fun buildGetValue(symbol: IrValueSymbol, origin: IrStatementOrigin = JsStatementOrigins.SYNTHESIZED_STATEMENT) =
+        IrGetValueImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, symbol.owner.type, symbol, origin)
 
     fun buildSetValue(symbol: IrValueSymbol, value: IrExpression) =
         IrSetValueImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, symbol.owner.type, symbol, value, JsStatementOrigins.SYNTHESIZED_STATEMENT)

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/AnnotationConstructorLowering.kt

@@ -5,17 +5,20 @@
 
 package org.jetbrains.kotlin.ir.backend.js.lower
 
-import org.jetbrains.kotlin.backend.common.CommonBackendContext
 import org.jetbrains.kotlin.backend.common.DeclarationTransformer
 import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.ir.backend.js.JsCommonBackendContext
 import org.jetbrains.kotlin.ir.declarations.IrConstructor
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.expressions.impl.IrDelegatingConstructorCallImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrInstanceInitializerCallImpl
+import org.jetbrains.kotlin.ir.util.constructors
 import org.jetbrains.kotlin.ir.util.parentAsClass
 
-class AnnotationConstructorLowering(context: CommonBackendContext) : DeclarationTransformer {
+class AnnotationConstructorLowering(val context: JsCommonBackendContext) : DeclarationTransformer {
 
     private val unitType = context.irBuiltIns.unitType
+    private val anyConstructor = context.irBuiltIns.anyClass.constructors.first()
 
     override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
         if (declaration !is IrConstructor || !declaration.isPrimary) return null
@@ -27,6 +30,9 @@ class AnnotationConstructorLowering(context: CommonBackendContext) : Declaration
         // put empty body to make sure proper initializer is generated
         // TODO what about its previous body?
         declaration.body = declaration.factory.createBlockBody(declaration.startOffset, declaration.endOffset) {
+            if (context.es6mode) {
+                statements += IrDelegatingConstructorCallImpl(startOffset, endOffset, context.irBuiltIns.anyType, anyConstructor, 0, 0)
+            }
             statements += IrInstanceInitializerCallImpl(startOffset, endOffset, irClass.symbol, unitType)
         }
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BlockDecomposerLowering.kt

@@ -36,9 +36,7 @@ class JsBlockDecomposerLowering(val context: JsIrBackendContext) : AbstractBlock
         JsIrBuilder.buildCall(context.intrinsics.unreachable, context.irBuiltIns.nothingType)
 }
 
-abstract class AbstractBlockDecomposerLowering(
-    private val context: JsCommonBackendContext
-) : BodyLoweringPass {
+abstract class AbstractBlockDecomposerLowering(private val context: JsCommonBackendContext) : BodyLoweringPass {
 
     private val nothingType = context.irBuiltIns.nothingType
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/CallableReferenceLowering.kt

@@ -179,7 +179,11 @@ class CallableReferenceLowering(private val context: CommonBackendContext) : Bod
                 origin = if (isKReference || !isLambda) FUNCTION_REFERENCE_IMPL else LAMBDA_IMPL
                 name = makeContextDependentName()
             }.apply {
-                superTypes = listOfNotNull(superClass, referenceType, secondFunctionInterface?.symbol?.typeWithArguments(referenceType.arguments))
+                superTypes = listOfNotNull(
+                    this@CallableReferenceBuilder.superClass,
+                    referenceType,
+                    secondFunctionInterface?.symbol?.typeWithArguments(referenceType.arguments)
+                )
 //                if (samSuperType == null)
 //                    superTypes += functionSuperClass.typeWith(parameterTypes)
 //                if (irFunctionReference.isSuspend) superTypes += context.ir.symbols.suspendFunctionInterface.defaultType

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/CaptureStackTraceInThrowables.kt

@@ -6,18 +6,23 @@
 package org.jetbrains.kotlin.ir.backend.js.lower
 
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
+import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
+import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
-import org.jetbrains.kotlin.ir.declarations.IrConstructor
-import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.backend.js.utils.Namer
+import org.jetbrains.kotlin.ir.builders.declarations.buildField
+import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrBlockBody
 import org.jetbrains.kotlin.ir.expressions.IrBody
 import org.jetbrains.kotlin.ir.expressions.IrDelegatingConstructorCall
 import org.jetbrains.kotlin.ir.expressions.impl.IrRawFunctionReferenceImpl
 import org.jetbrains.kotlin.ir.util.isSubclassOf
 import org.jetbrains.kotlin.ir.util.parentAsClass
+import org.jetbrains.kotlin.name.Name
 
+object ES6_THROWABLE_CONSTRUCTOR_SLOT : IrDeclarationOriginImpl("ES6_THROWABLE_CONSTRUCTOR_SLOT")
 /**
  * Capture stack trace in primary constructors of Throwable
  */
@@ -31,15 +36,36 @@ class CaptureStackTraceInThrowables(val context: JsIrBackendContext) : BodyLower
         if (!klass.isSubclassOf(context.irBuiltIns.throwableClass.owner))
             return
 
-        val statements = (irBody as IrBlockBody).statements
+        val statements = (irBody as? IrBlockBody)?.statements ?: return
         val delegatingConstructorCallIndex = statements.indexOfLast { it is IrDelegatingConstructorCall }
 
         statements.add(delegatingConstructorCallIndex + 1, JsIrBuilder.buildCall(context.intrinsics.captureStack).also { call ->
-            call.putValueArgument(0, JsIrBuilder.buildGetValue(klass.thisReceiver!!.symbol))
-            call.putValueArgument(
-                1,
-                IrRawFunctionReferenceImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, context.irBuiltIns.anyType, container.symbol)
-            )
+            val self = klass.thisReceiver!!.symbol
+
+            val constructorRef = if (context.es6mode) {
+                JsIrBuilder.buildGetField(klass.addThrowableConstructorSlot().symbol, JsIrBuilder.buildGetValue(self))
+            } else {
+                JsIrBuilder.buildRawReference(container.symbol, context.irBuiltIns.anyType)
+            }
+
+            call.putValueArgument(0, JsIrBuilder.buildGetValue(self))
+            call.putValueArgument(1, constructorRef)
         })
     }
+
+    private fun IrClass.addThrowableConstructorSlot(): IrField {
+        return factory.buildField {
+            type = context.dynamicType
+            isFinal = false
+            isExternal = false
+            isStatic = false
+            metadata = null
+            name = Name.identifier(Namer.THROWABLE_CONSTRUCTOR)
+            visibility = DescriptorVisibilities.PRIVATE
+            origin = ES6_THROWABLE_CONSTRUCTOR_SLOT
+        }.apply {
+            parent = this@addThrowableConstructorSlot
+            declarations.add(this)
+        }
+    }
 }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ConstLowering.kt

@@ -8,14 +8,20 @@ package org.jetbrains.kotlin.ir.backend.js.lower
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
 import org.jetbrains.kotlin.backend.common.compilationException
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.utils.getVoid
+import org.jetbrains.kotlin.ir.declarations.IrConstructor
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.expressions.IrBody
 import org.jetbrains.kotlin.ir.expressions.IrConst
 import org.jetbrains.kotlin.ir.expressions.IrConstKind
 import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstructorCallImpl
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrConstructorSymbol
+import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.classifierOrNull
 import org.jetbrains.kotlin.ir.types.defaultType
@@ -33,7 +39,13 @@ class ConstTransformer(private val context: JsIrBackendContext) : IrElementTrans
     ): IrExpression {
         val constructor = irClass.constructors.single { it.owner.isPrimary }
         val argType = constructor.owner.valueParameters.first().type
-        return IrConstructorCallImpl.fromSymbolOwner(expression.startOffset, expression.endOffset, irClass.defaultType, constructor).apply {
+
+        return IrConstructorCallImpl.fromSymbolOwner(
+                expression.startOffset,
+                expression.endOffset,
+                irClass.defaultType,
+                constructor
+            ).apply {
             for (i in args.indices) {
                 putValueArgument(i, carrierFactory(startOffset, endOffset, argType, args[i]))
             }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ES6AddBoxParameterLowering.kt

@@ -0,0 +1,182 @@
+/*
+ * Copyright 2010-2020 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.ir.backend.js.lower
+
+import org.jetbrains.kotlin.backend.common.DeclarationTransformer
+import org.jetbrains.kotlin.backend.common.ir.ValueRemapper
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
+import org.jetbrains.kotlin.ir.backend.js.utils.getVoid
+import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
+import org.jetbrains.kotlin.ir.backend.js.utils.hasStrictSignature
+import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.builders.*
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.symbols.IrValueSymbol
+import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
+import org.jetbrains.kotlin.ir.backend.js.utils.Namer
+import org.jetbrains.kotlin.ir.types.makeNullable
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
+import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
+
+object ES6_BOX_PARAMETER : IrDeclarationOriginImpl("ES6_BOX_PARAMETER")
+object ES6_BOX_PARAMETER_DEFAULT_RESOLUTION : IrStatementOriginImpl("ES6_BOX_PARAMETER_DEFAULT_RESOLUTION")
+
+val IrValueParameter.isBoxParameter: Boolean
+    get() = origin == ES6_BOX_PARAMETER
+
+val IrWhen.isBoxParameterDefaultResolution: Boolean
+    get() = origin == ES6_BOX_PARAMETER_DEFAULT_RESOLUTION
+
+val IrFunction.boxParameter: IrValueParameter?
+    get() = valueParameters.lastOrNull()?.takeIf { it.isBoxParameter }
+
+class ES6AddBoxParameterToConstructorsLowering(val context: JsIrBackendContext) : DeclarationTransformer {
+    override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
+        if (!context.es6mode || declaration !is IrConstructor || declaration.hasStrictSignature(context)) return null
+
+        hackEnums(declaration)
+        hackExceptions(declaration)
+        hackSimpleClassWithCapturing(declaration)
+
+        if (!declaration.isSyntheticPrimaryConstructor) {
+            declaration.addBoxParameter()
+        }
+
+        return null
+    }
+
+    private fun IrConstructor.addBoxParameter() {
+        val irClass = parentAsClass
+        val boxParameter = generateBoxParameter(irClass).also { valueParameters += it }
+
+        val body = body as? IrBlockBody ?: return
+        val isBoxUsed = body.replaceThisWithBoxBeforeSuperCall(irClass, boxParameter.symbol)
+
+        if (isBoxUsed) {
+            body.statements.add(0, boxParameter.generateDefaultResolution())
+        }
+    }
+
+    private fun createJsObjectLiteral(): IrExpression {
+        return JsIrBuilder.buildCall(context.intrinsics.jsEmptyObject)
+    }
+
+    private fun IrConstructor.generateBoxParameter(irClass: IrClass): IrValueParameter {
+        return JsIrBuilder.buildValueParameter(
+            parent = this,
+            name = Namer.ES6_BOX_PARAMETER_NAME,
+            index = valueParameters.size,
+            type = irClass.defaultType.makeNullable(),
+            origin = ES6_BOX_PARAMETER,
+            isAssignable = true
+        )
+    }
+
+    private fun IrValueParameter.generateDefaultResolution(): IrExpression {
+        return with(context.createIrBuilder(symbol, UNDEFINED_OFFSET, UNDEFINED_OFFSET)) {
+            irIfThen(
+                context.irBuiltIns.unitType,
+                irEqeqeqWithoutBox(irGet(type, symbol), this@ES6AddBoxParameterToConstructorsLowering.context.getVoid()),
+                irSet(symbol, createJsObjectLiteral()),
+                ES6_BOX_PARAMETER_DEFAULT_RESOLUTION
+            )
+        }
+    }
+
+    private fun IrBody.replaceThisWithBoxBeforeSuperCall(irClass: IrClass, boxParameterSymbol: IrValueSymbol): Boolean {
+        var meetCapturing = false
+        var meetDelegatingConstructor = false
+        val selfParameterSymbol = irClass.thisReceiver!!.symbol
+
+        transformChildrenVoid(object : ValueRemapper(mapOf(selfParameterSymbol to boxParameterSymbol)) {
+            override fun visitGetValue(expression: IrGetValue): IrExpression {
+                return if (meetDelegatingConstructor) {
+                    expression
+                } else {
+                    super.visitGetValue(expression)
+                }
+            }
+
+            override fun visitSetField(expression: IrSetField): IrExpression {
+                if (meetDelegatingConstructor) return expression
+                val newExpression = super.visitSetField(expression)
+                val receiver = expression.receiver as? IrGetValue
+
+                if (receiver?.symbol == boxParameterSymbol) {
+                    meetCapturing = true
+                }
+
+                return newExpression
+            }
+
+            override fun visitDelegatingConstructorCall(expression: IrDelegatingConstructorCall): IrExpression {
+                meetDelegatingConstructor = true
+                return super.visitDelegatingConstructorCall(expression)
+            }
+        })
+
+        return meetCapturing
+    }
+
+    private fun hackEnums(constructor: IrConstructor) {
+        constructor.transformChildren(object : IrElementTransformerVoid() {
+            override fun visitTypeOperator(expression: IrTypeOperatorCall): IrExpression {
+                return (expression.argument as? IrDelegatingConstructorCall) ?: expression
+            }
+        }, null)
+    }
+
+    private fun hackSimpleClassWithCapturing(constructor: IrConstructor) {
+        val irClass = constructor.parentAsClass
+
+        if (irClass.superClass != null || (!irClass.isInner && !irClass.isLocal)) return
+
+        val statements = (constructor.body as? IrBlockBody)?.statements ?: return
+        val delegationConstructorIndex = statements.indexOfFirst { it is IrDelegatingConstructorCall }
+
+        if (delegationConstructorIndex == -1) return
+
+        val firstClassFieldAssignment = statements.indexOfFirst { statement ->
+            statement is IrSetField && statement.receiver?.let { it is IrGetValue && it.symbol == irClass.thisReceiver?.symbol } == true
+        }
+
+        if (firstClassFieldAssignment == -1 || firstClassFieldAssignment > delegationConstructorIndex) return
+
+        statements.add(firstClassFieldAssignment, statements[delegationConstructorIndex])
+        statements.removeAt(delegationConstructorIndex + 1)
+    }
+
+    /**
+     * Swap call synthetic primary ctor and call extendThrowable
+     */
+    private fun hackExceptions(constructor: IrConstructor) {
+        val setPropertiesSymbol = context.setPropertiesToThrowableInstanceSymbol
+
+        val statements = (constructor.body as? IrBlockBody)?.statements ?: return
+
+        var callIndex = -1
+        var superCallIndex = -1
+        for (i in statements.indices) {
+            val s = statements[i]
+
+            if (s is IrCall && s.symbol === setPropertiesSymbol) {
+                callIndex = i
+            }
+            if (s is IrDelegatingConstructorCall && s.symbol.owner.origin === PrimaryConstructorLowering.SYNTHETIC_PRIMARY_CONSTRUCTOR) {
+                superCallIndex = i
+            }
+        }
+
+        if (callIndex != -1 && superCallIndex != -1) {
+            val tmp = statements[callIndex]
+            statements[callIndex] = statements[superCallIndex]
+            statements[superCallIndex] = tmp
+        }
+    }
+}
+

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ES6AddInternalParametersToConstructorPhase.kt

@@ -1,216 +0,0 @@
-/*
- * Copyright 2010-2020 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.ir.backend.js.lower
-
-import org.jetbrains.kotlin.backend.common.BodyLoweringPass
-import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
-import org.jetbrains.kotlin.descriptors.Modality
-import org.jetbrains.kotlin.ir.IrStatement
-import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
-import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
-import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
-import org.jetbrains.kotlin.ir.backend.js.lower.PrimaryConstructorLowering.SYNTHETIC_PRIMARY_CONSTRUCTOR
-import org.jetbrains.kotlin.ir.builders.declarations.addValueParameter
-import org.jetbrains.kotlin.ir.builders.declarations.buildFun
-import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.expressions.*
-import org.jetbrains.kotlin.ir.expressions.impl.IrConstructorCallImpl
-import org.jetbrains.kotlin.ir.expressions.impl.IrDelegatingConstructorCallImpl
-import org.jetbrains.kotlin.ir.expressions.impl.IrGetValueImpl
-import org.jetbrains.kotlin.ir.types.isAny
-import org.jetbrains.kotlin.ir.util.defaultType
-import org.jetbrains.kotlin.ir.util.parentAsClass
-import org.jetbrains.kotlin.ir.util.statements
-import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
-import org.jetbrains.kotlin.name.Name
-
-/**
- * Add ES6_INIT_BOX_PARAMETER for each constructor (except constructors
- * of inline, external and primitive (string, arrays) classes).
- * Uses: Inline class's constructor initialize field of outer class before
- * call `super`, but its impossible in ES6. ES6_INIT_BOX_PARAMETER - object,
- * that collect these values and pass to super constructor. In the last
- * constructor of delegation chain ES6_INIT_BOX_PARAMETER will be open
- * with `Object.assign(this, box)`
- *
- * Add ES6_RESULT_TYPE PARAMETER for each secondary ctor (except
- * constructors of external and primitive (string, arrays) classes).
- * Uses: Pass information about type of new object to `Reflect.construct()`
- *
- * Transform SYNTHETIC_PRIMARY_CONSTRUCTOR:
- * constructor() {
- *   //statements
- * }
- * ==>
- * constructor() {
- *   init(this)
- * }
- * init($this$) {
- *   //statements from ctor
- * }
- */
-class ES6AddInternalParametersToConstructorPhase(val context: JsIrBackendContext) : BodyLoweringPass {
-    object ES6_SYNTHETIC_PRIMARY_INIT_FUNCTION : IrDeclarationOriginImpl("ES6_SYNTHETIC_PRIMARY_INIT_FUNCTION")
-    object ES6_INIT_BOX_PARAMETER : IrDeclarationOriginImpl("ES6_INIT_BOX_PARAMETER")
-    object ES6_RESULT_TYPE_PARAMETER : IrDeclarationOriginImpl("ES6_RESULT_TYPE_PARAMETER")
-
-    override fun lower(irBody: IrBody, container: IrDeclaration) {
-        if (!context.es6mode) return
-
-        container.transform(CallSiteTransformer(), null)
-
-        if (container !is IrConstructor) return
-
-        if (!container.hasStrictSignature()) container.addInternalValueParameters()
-
-        if (container.origin === SYNTHETIC_PRIMARY_CONSTRUCTOR) {
-            createInitFunction(container)
-            openInitializerBox(container)
-        }
-    }
-
-    private fun IrConstructor.addInternalValueParameters() {
-        addValueParameter("box", context.dynamicType, ES6_INIT_BOX_PARAMETER)
-
-        if (!isPrimary) {
-            addValueParameter("resultType", context.dynamicType, ES6_RESULT_TYPE_PARAMETER)
-        }
-    }
-
-    private fun createInitFunction(constructor: IrConstructor) {
-        val irClass = constructor.parentAsClass
-        val initFunction = buildInitFunction(constructor, irClass)
-        irClass.declarations += initFunction
-
-        context.mapping.constructorToInitFunction[constructor] = initFunction
-
-        initFunction.transformChildren(object : IrElementTransformerVoid() {
-            override fun visitDeclaration(declaration: IrDeclarationBase): IrStatement {
-                declaration.parent = initFunction
-                return declaration
-            }
-        }, null)
-    }
-
-    private fun openInitializerBox(constructor: IrConstructor) = with(constructor.body as IrBlockBody) {
-        statements.clear()
-        statements += JsIrBuilder.buildCall(context.intrinsics.jsOpenInitializerBox).also {
-            it.putValueArgument(0, JsIrBuilder.buildGetValue(constructor.parentAsClass.thisReceiver!!.symbol))
-            it.putValueArgument(1, JsIrBuilder.buildGetValue(constructor.valueParameters.last().symbol))
-        }
-    }
-
-    private fun buildInitFunction(constructor: IrConstructor, irClass: IrClass): IrSimpleFunction {
-        val functionName = "${irClass.name}_init"
-
-        return context.irFactory.buildFun {
-            name = Name.identifier(functionName)
-            returnType = context.irBuiltIns.unitType
-            visibility = DescriptorVisibilities.PROTECTED
-            modality = Modality.FINAL
-            isInline = constructor.isInline
-            isExternal = constructor.isExternal
-            origin = ES6_SYNTHETIC_PRIMARY_INIT_FUNCTION
-        }.apply {
-            parent = irClass
-            addValueParameter("\$this\$", context.dynamicType)
-
-            body = context.irFactory.createBlockBody(UNDEFINED_OFFSET, UNDEFINED_OFFSET, constructor.body?.statements.orEmpty())
-
-            transformChildren(object : IrElementTransformerVoid() {
-                override fun visitGetValue(expression: IrGetValue): IrExpression {
-                    return if (expression.symbol.owner === constructor.parentAsClass.thisReceiver!!) {
-                        with(expression) { IrGetValueImpl(startOffset, endOffset, type, valueParameters.single().symbol) }
-                    } else {
-                        expression
-                    }
-                }
-            }, null)
-        }
-    }
-
-    /**
-     * Pass `null` for ES6_INIT_BOX_PARAMETER and ES6_RESULT_TYPE_PARAMETER
-     */
-    inner class CallSiteTransformer : IrElementTransformerVoid() {
-        override fun visitConstructorCall(expression: IrConstructorCall): IrExpression {
-            val constructor = expression.symbol.owner
-            val parent = constructor.parentAsClass
-
-            if (constructor.hasStrictSignature() || parent.defaultType.isAny()) return expression
-
-            val newArgsCount = if (constructor.isPrimary) 1 else 2
-            return expression.run {
-                IrConstructorCallImpl(
-                    startOffset,
-                    endOffset,
-                    type,
-                    symbol,
-                    typeArgumentsCount,
-                    constructorTypeArgumentsCount,
-                    valueArgumentsCount + newArgsCount
-                ).also {
-                    for (i in 0 until valueArgumentsCount) {
-                        it.putValueArgument(i, getValueArgument(i))
-                    }
-
-                    it.putValueArgument(
-                        valueArgumentsCount,
-                        JsIrBuilder.buildNull(context.dynamicType)
-                    )
-
-                    if (!constructor.isPrimary) {
-                        it.putValueArgument(
-                            valueArgumentsCount + 1,
-                            JsIrBuilder.buildNull(context.dynamicType)
-                        )
-                    }
-                }
-            }
-        }
-
-        override fun visitDelegatingConstructorCall(expression: IrDelegatingConstructorCall): IrExpression {
-            val constructor = expression.symbol.owner
-            val parent = constructor.parentAsClass
-
-            if (constructor.hasStrictSignature() || parent.defaultType.isAny()) return expression
-
-            val newArgsCount = if (constructor.isPrimary) 1 else 2
-
-            return expression.run {
-                IrDelegatingConstructorCallImpl(
-                    startOffset,
-                    endOffset,
-                    type,
-                    symbol,
-                    typeArgumentsCount,
-                    valueArgumentsCount + newArgsCount
-                ).also {
-                    for (i in 0 until valueArgumentsCount) {
-                        it.putValueArgument(i, getValueArgument(i))
-                    }
-
-                    it.putValueArgument(
-                        valueArgumentsCount,
-                        JsIrBuilder.buildNull(context.dynamicType)
-                    )
-
-                    if (!constructor.isPrimary) {
-                        it.putValueArgument(
-                            valueArgumentsCount + 1,
-                            JsIrBuilder.buildNull(context.dynamicType)
-                        )
-                    }
-                }
-            }
-        }
-    }
-
-    private fun IrConstructor.hasStrictSignature(): Boolean {
-        val primitives = with(context.irBuiltIns) { primitiveTypesToPrimitiveArrays.values + stringClass }
-        return with(parentAsClass) { isExternal || context.inlineClassesUtils.isClassInlineLike(this) || symbol in primitives }
-    }
-}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ES6ConstructorBoxParameterOptimizationLowering.kt

@@ -0,0 +1,140 @@
+/*
+ * Copyright 2010-2022 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.ir.backend.js.lower
+
+import org.jetbrains.kotlin.backend.common.BodyLoweringPass
+import org.jetbrains.kotlin.backend.common.DeclarationTransformer
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.utils.getVoid
+import org.jetbrains.kotlin.ir.backend.js.utils.irEmpty
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
+import org.jetbrains.kotlin.ir.util.isLocal
+import org.jetbrains.kotlin.ir.util.parentAsClass
+import org.jetbrains.kotlin.ir.util.superClass
+import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
+import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
+import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
+import org.jetbrains.kotlin.util.collectionUtils.filterIsInstanceAnd
+
+class ES6ConstructorBoxParameterOptimizationLowering(private val context: JsIrBackendContext) : BodyLoweringPass {
+    private val esClassWhichNeedBoxParameters = context.mapping.esClassWhichNeedBoxParameters
+
+    override fun lower(irBody: IrBody, container: IrDeclaration) {
+        if (!context.es6mode) return
+
+        val containerFunction = container as? IrFunction
+
+        val shouldRemoveBoxRelatedDeclarationsAndStatements =
+            containerFunction?.isEs6ConstructorReplacement == true && !containerFunction.parentAsClass.requiredToHaveBoxParameter()
+
+        if (containerFunction != null && shouldRemoveBoxRelatedDeclarationsAndStatements && irBody is IrBlockBody) {
+            containerFunction.valueParameters = containerFunction.valueParameters.filter { !it.isBoxParameter }
+        }
+
+        irBody.transformChildrenVoid(object : IrElementTransformerVoid() {
+            override fun visitWhen(expression: IrWhen): IrExpression {
+                return if (shouldRemoveBoxRelatedDeclarationsAndStatements && expression.isBoxParameterDefaultResolution) {
+                    irEmpty(context)
+                } else {
+                    super.visitWhen(expression)
+                }
+            }
+
+            override fun visitCall(expression: IrCall): IrExpression {
+                val callee = expression.symbol.owner
+
+                return when {
+                    shouldRemoveBoxRelatedDeclarationsAndStatements && (callee.symbol == context.intrinsics.jsCreateThisSymbol || callee.symbol == context.intrinsics.jsCreateExternalThisSymbol) -> {
+                        expression.putValueArgument(expression.valueArgumentsCount - 1, context.getVoid())
+                        super.visitCall(expression)
+                    }
+                    callee.isEs6ConstructorReplacement && (!callee.parentAsClass.requiredToHaveBoxParameter() || shouldRemoveBoxRelatedDeclarationsAndStatements) -> {
+                        val newArgumentsSize = expression.valueArgumentsCount - 1
+                        super.visitCall(IrCallImpl(
+                            expression.startOffset,
+                            expression.endOffset,
+                            expression.type,
+                            expression.symbol,
+                            expression.typeArgumentsCount,
+                            newArgumentsSize,
+                            expression.origin,
+                            superQualifierSymbol = expression.superQualifierSymbol
+                        ).apply {
+                            copyTypeArgumentsFrom(expression)
+
+                            dispatchReceiver = expression.dispatchReceiver
+                            extensionReceiver = expression.extensionReceiver
+
+                            for (i in 0 until newArgumentsSize) {
+                                putValueArgument(i, expression.getValueArgument(i))
+                            }
+                        })
+                    }
+                    else -> super.visitCall(expression)
+                }
+            }
+        })
+    }
+
+    private fun IrClass.requiredToHaveBoxParameter(): Boolean {
+        return esClassWhichNeedBoxParameters.contains(this)
+    }
+}
+
+class ES6CollectConstructorsWhichNeedBoxParameters(private val context: JsIrBackendContext) : DeclarationTransformer {
+    private val esClassWhichNeedBoxParameters = context.mapping.esClassWhichNeedBoxParameters
+
+    override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
+        if (!context.es6mode || declaration !is IrClass) return null
+
+        val hasSuperClass = declaration.superClass != null
+
+        if (hasSuperClass && declaration.isInner) {
+            declaration.addToClassListWhichNeedBoxParameter()
+        }
+        if (hasSuperClass && declaration.isLocal && declaration.containsCapturedValues()) {
+            declaration.addToClassListWhichNeedBoxParameter()
+        }
+
+        return null
+    }
+
+    private fun IrClass.containsCapturedValues(): Boolean {
+        if (superClass == null) return false
+
+        declarations
+            .filterIsInstanceAnd<IrFunction> { it.isEs6ConstructorReplacement }
+            .forEach {
+                var meetCapturing = false
+                val boxParameter = it.boxParameter
+
+                it.body?.acceptChildrenVoid(object : IrElementVisitorVoid {
+                    override fun visitSetField(expression: IrSetField) {
+                        val receiver = expression.receiver as? IrGetValue
+                        if (receiver != null && receiver.symbol == boxParameter?.symbol) {
+                            meetCapturing = true
+                        }
+                        super.visitSetField(expression)
+                    }
+                })
+
+                if (meetCapturing) return true
+            }
+
+        return false
+    }
+
+    private fun IrClass.addToClassListWhichNeedBoxParameter() {
+        if (isExternal) return
+        esClassWhichNeedBoxParameters.add(this)
+        superClass?.addToClassListWhichNeedBoxParameter()
+    }
+}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ES6ConstructorCallLowering.kt

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2010-2020 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.ir.backend.js.lower
+
+import org.jetbrains.kotlin.backend.common.BodyLoweringPass
+import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.JsStatementOrigins
+import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
+import org.jetbrains.kotlin.ir.backend.js.utils.hasStrictSignature
+import org.jetbrains.kotlin.ir.backend.js.utils.jsConstructorReference
+import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
+
+class ES6ConstructorCallLowering(val context: JsIrBackendContext) : BodyLoweringPass {
+    private var IrConstructor.constructorFactory by context.mapping.secondaryConstructorToFactory
+
+    override fun lower(irBody: IrBody, container: IrDeclaration) {
+        if (!context.es6mode) return
+
+        val containerFunction = container as? IrFunction
+
+        irBody.transformChildrenVoid(object : IrElementTransformerVoidWithContext() {
+            override fun visitConstructorCall(expression: IrConstructorCall): IrExpression {
+                val currentConstructor = expression.symbol.owner
+                val irClass = currentConstructor.parentAsClass
+                val currentFunction = currentFunction?.irElement as? IrFunction ?: containerFunction
+
+                if (irClass.symbol == context.irBuiltIns.anyClass || currentConstructor.hasStrictSignature(context)) {
+                    return super.visitConstructorCall(expression)
+                }
+
+                val factoryFunction = currentConstructor.constructorFactory ?: error("Replacement for the constructor is not found")
+
+                if (expression.isInitCall) {
+                    assert(factoryFunction.isInitFunction) { "Expect to have init function replacement" }
+                    return JsIrBuilder.buildCall(factoryFunction.symbol).apply {
+                        copyValueArgumentsFrom(expression, factoryFunction)
+                    }
+                }
+
+                val isDelegatingCall =
+                    expression.isSyntheticDelegatingReplacement && currentFunction != null && currentFunction.parentAsClass != irClass
+
+                val factoryFunctionCall = JsIrBuilder.buildCall(
+                    factoryFunction.symbol,
+                    superQualifierSymbol = irClass.symbol.takeIf { isDelegatingCall },
+                    origin = if (isDelegatingCall) ES6_DELEGATING_CONSTRUCTOR_REPLACEMENT else JsStatementOrigins.SYNTHESIZED_STATEMENT
+                ).apply {
+                    copyValueArgumentsFrom(expression, factoryFunction)
+
+                    if (expression.isSyntheticDelegatingReplacement) {
+                        currentFunction?.boxParameter?.let {
+                            putValueArgument(valueArgumentsCount - 1, JsIrBuilder.buildGetValue(it.symbol))
+                        }
+                        if (superQualifierSymbol == null) {
+                            dispatchReceiver = JsIrBuilder.buildGetValue(factoryFunction.dispatchReceiverParameter!!.symbol)
+                        }
+                    } else {
+                        dispatchReceiver = irClass.jsConstructorReference(context)
+                    }
+                }
+
+                return super.visitCall(factoryFunctionCall)
+            }
+        })
+    }
+}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ES6ConstructorLowering.kt

@@ -5,568 +5,253 @@
 
 package org.jetbrains.kotlin.ir.backend.js.lower
 
-import org.jetbrains.kotlin.backend.common.BodyLoweringPass
-import org.jetbrains.kotlin.ir.IrElement
-import org.jetbrains.kotlin.ir.IrStatement
+import org.jetbrains.kotlin.backend.common.DeclarationTransformer
+import org.jetbrains.kotlin.backend.common.ir.ValueRemapper
+import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
+import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.export.isExported
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
-import org.jetbrains.kotlin.ir.backend.js.lower.ES6AddInternalParametersToConstructorPhase.ES6_INIT_BOX_PARAMETER
-import org.jetbrains.kotlin.ir.backend.js.lower.ES6AddInternalParametersToConstructorPhase.ES6_RESULT_TYPE_PARAMETER
-import org.jetbrains.kotlin.ir.backend.js.lower.PrimaryConstructorLowering.SYNTHETIC_PRIMARY_CONSTRUCTOR
-import org.jetbrains.kotlin.ir.builders.declarations.addValueParameter
+import org.jetbrains.kotlin.ir.backend.js.utils.*
 import org.jetbrains.kotlin.ir.builders.declarations.buildFun
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
-import org.jetbrains.kotlin.ir.expressions.impl.IrGetValueImpl
-import org.jetbrains.kotlin.ir.expressions.impl.IrVarargImpl
 import org.jetbrains.kotlin.ir.symbols.IrValueSymbol
-import org.jetbrains.kotlin.ir.symbols.IrVariableSymbol
-import org.jetbrains.kotlin.ir.types.isAny
-import org.jetbrains.kotlin.ir.util.defaultType
-import org.jetbrains.kotlin.ir.util.parentAsClass
-import org.jetbrains.kotlin.ir.util.statements
-import org.jetbrains.kotlin.ir.util.transformInPlace
-import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
-import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
+import org.jetbrains.kotlin.ir.types.typeWith
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
-object ES6_THIS_VARIABLE_ORIGIN : IrDeclarationOriginImpl("ES6_THIS_VARIABLE_ORIGIN")
+object ES6_INIT_CALL : IrStatementOriginImpl("ES6_INIT_CALL")
+object ES6_CONSTRUCTOR_REPLACEMENT : IrDeclarationOriginImpl("ES6_CONSTRUCTOR_REPLACEMENT")
+object ES6_PRIMARY_CONSTRUCTOR_REPLACEMENT : IrDeclarationOriginImpl("ES6_PRIMARY_CONSTRUCTOR_REPLACEMENT")
+object ES6_INIT_FUNCTION : IrDeclarationOriginImpl("ES6_INIT_FUNCTION")
+object ES6_DELEGATING_CONSTRUCTOR_REPLACEMENT : IrStatementOriginImpl("ES6_DELEGATING_CONSTRUCTOR_REPLACEMENT")
 
-class ES6ConstructorLowering(val context: JsIrBackendContext) : BodyLoweringPass {
-    override fun lower(irBody: IrBody, container: IrDeclaration) {
-        if (!context.es6mode) return
+val IrDeclaration.isEs6ConstructorReplacement: Boolean
+    get() = origin == ES6_CONSTRUCTOR_REPLACEMENT || origin == ES6_PRIMARY_CONSTRUCTOR_REPLACEMENT
 
-        if (container !is IrConstructor) return
+val IrDeclaration.isEs6PrimaryConstructorReplacement: Boolean
+    get() = origin == ES6_PRIMARY_CONSTRUCTOR_REPLACEMENT
 
-        if (container.hasStrictSignature()) return
+val IrFunctionAccessExpression.isSyntheticDelegatingReplacement: Boolean
+    get() = origin == ES6_DELEGATING_CONSTRUCTOR_REPLACEMENT
 
-        hackEnums(container)
-        hackExceptions(context, container)
+val IrDeclaration.isInitFunction: Boolean
+    get() = origin == ES6_INIT_FUNCTION
 
-        val superCall = getSuperCall(container) ?: return
-        val superCtor = superCall.symbol.owner
-        val helper = LowerCtorHelper(context, container, superCtor)
+val IrFunctionAccessExpression.isInitCall: Boolean
+    get() = origin == ES6_INIT_CALL
 
-        if (container.isPrimary) {
-            if (superCtor.isPrimary) primaryToPrimary(helper)
-            else primaryToSecondary(helper)
+class ES6ConstructorLowering(val context: JsIrBackendContext) : DeclarationTransformer {
+    private var IrConstructor.constructorFactory by context.mapping.secondaryConstructorToFactory
+
+    override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
+        if (!context.es6mode || declaration !is IrConstructor || declaration.hasStrictSignature(context)) return null
+
+        return if (declaration.isSyntheticPrimaryConstructor) {
+            listOf(declaration.generateInitFunction())
         } else {
-            if (superCtor.isPrimary) secondaryToPrimary(helper)
-            else secondaryToSecondary(helper)
-
-            replaceCallToDefaultPrimary(context, container)
-            changeIrConstructorToIrFunction(context, container)
+            val factoryFunction = declaration.generateCreateFunction()
+            listOfNotNull(factoryFunction, declaration.generateExportedConstructorIfNeed(factoryFunction))
         }
     }
 
-    /**
-     * constructor(args, box) {
-     *   var currBox = box || {}
-     *
-     *   //1. Superclass is Any
-     *   Object.assign(this, currBox)
-     *   //body
-     *
-     *   //2. Base class isInline or isExternal or array/string
-     *   super(args)
-     *   Object.assign(this, currBox)
-     *   //body
-     *
-     *   //3. Base class !isInline and !isExternal and !(array/string)
-     *   //fill initialization box
-     *   super(args, currBox)
-     *   //body
-     * }
-     */
-    private fun primaryToPrimary(helper: LowerCtorHelper) = with(helper) {
-        statements.add(0, boxOrEmptyObject)
-
-        if (superCtor.parentAsClass.defaultType.isAny()) {
-            //after superCall
-            statements.add(1, openBoxStatement(thisSymbol, boxSymbol))
-            return
-        }
-
-        if (superCtor.hasStrictSignature()) {
-            //after superCall
-            statements.add(2, openBoxStatement(thisSymbol, boxSymbol))
-        } else {
-            fillInitializerBox(boxSymbol, constructor)
-            putBoxToSuperCall(boxSymbol, constructor)
-        }
-    }
-
-    /**
-     * constructor(args, box) {
-     *   var currBox = box || {}
-     *
-     *   //1. Base class isExternal or array/string
-     *   var $this$ = Base_constructor(.., currBox)
-     *   Object.assign(this, currBox)
-     *   return $this$
-     *
-     *   //2. Base class !isInline and !isExternal and !(array/string)
-     *   //fill initialization box
-     *   var $this$ = Base_constructor(.., currBox, new.target)
-     *   //body
-     *   return $this$
-     * }
-     */
-    private fun primaryToSecondary(helper: LowerCtorHelper) = with(helper) {
-        statements.add(0, boxOrEmptyObject)
-
-        if (superCtor.hasStrictSignature()) {
-            fun createNewSuperCall(): IrCall {
-                val callType = JsIrBuilder.buildCall(context.intrinsics.jsClass, context.dynamicType, listOf(superCtor.returnType))
-                val newTarget = JsIrBuilder.buildCall(context.intrinsics.jsNewTarget)
-                val args = IrVarargImpl(
-                    UNDEFINED_OFFSET, UNDEFINED_OFFSET,
-                    context.dynamicType,
-                    context.dynamicType,
-                    getElements(constructor)
-                )
-
-                return JsIrBuilder.buildCall(context.intrinsics.jsConstruct).apply {
-                    putValueArgument(0, callType)
-                    putValueArgument(1, newTarget)
-                    putValueArgument(2, args)
-
-                    putTypeArgument(0, superCtor.returnType)
+    private fun IrConstructor.generateExportedConstructorIfNeed(factoryFunction: IrSimpleFunction): IrConstructor? {
+        return runIf(isExported(context) && isPrimary) {
+            apply {
+                valueParameters = valueParameters.filterNot { it.isBoxParameter }
+                (body as? IrBlockBody)?.let {
+                    val selfReplacedConstructorCall = JsIrBuilder.buildCall(factoryFunction.symbol).apply {
+                        valueParameters.forEachIndexed { i, it -> putValueArgument(i, JsIrBuilder.buildGetValue(it.symbol)) }
+                        dispatchReceiver = JsIrBuilder.buildCall(context.intrinsics.jsNewTarget)
+                    }
+                    it.statements.add(JsIrBuilder.buildReturn(symbol, selfReplacedConstructorCall, returnType))
                 }
             }
-
-            val newThis = createThisVariable(createNewSuperCall())
-            changeReturnUnitToReturnInstance(newThis)
-
-            statements.add(2, openBoxStatement(newThis.symbol, boxSymbol))
-            statements += returnThis(constructor, newThis)
-
-            redirectOldThisToNewOne(constructor, newThis)
-        } else {
-            putBoxToSuperCall(boxSymbol, constructor)
-            fillInitializerBox(boxSymbol, constructor)
-
-            val newTarget = JsIrBuilder.buildCall(context.intrinsics.jsNewTarget)
-            val newThis = createThisVariable(createNewSuperCallPrimaryToSecondary(superCall, newTarget))
-            changeReturnUnitToReturnInstance(newThis)
-
-            statements += returnThis(constructor, newThis)
-
-            redirectOldThisToNewOne(constructor, newThis)
         }
     }
 
-    /**
-     * Derived_constructor(.., box, resultType) {
-     *   var currBox = box || {}
-     *   var currResultType = resultType || Derived
-     *
-     *   //1. Base class isInline or isExternal or array/string
-     *   var $this$ = construct(Base, currResultType, [..])
-     *   Object.assign(this, currBox)
-     *   //body
-     *   return $this$
-     *
-     *   //2. Base class !isInline and !isExternal and !(array/string)
-     *   //fill initialization box
-     *   var $this$ = construct(Base, currResultType, [.., currBox])
-     *   //body
-     *   return $this$
-     * }
-     */
-    private fun secondaryToPrimary(helper: LowerCtorHelper) = with(helper) {
-        statements.add(0, boxOrEmptyObject)
-        statements.add(1, resultTypeOrDefaultType())
-        val resultTypeSymbol = (statements[1] as IrVariable).symbol
+    private fun IrConstructor.generateInitFunction(): IrSimpleFunction {
+        val constructor = this
+        val irClass = parentAsClass
+        val constructorName = "init_${irClass.constructorPostfix}"
+        return context.irFactory.buildFun {
+            name = Name.identifier(constructorName)
+            returnType = context.irBuiltIns.unitType
+            visibility = DescriptorVisibilities.PRIVATE
+            modality = Modality.FINAL
+            isInline = constructor.isInline
+            isExternal = constructor.isExternal
+            origin = ES6_INIT_FUNCTION
+        }.also { factory ->
+            factory.parent = irClass
+            factory.copyTypeParametersFrom(irClass)
+            factory.annotations = annotations
+            factory.extensionReceiverParameter = irClass.thisReceiver?.copyTo(factory)
 
-        if (superCtor.hasStrictSignature()) {
-            val newThis = createThisVariable(createNewSuperCallSecondaryToPrimary(constructor, superCtor, resultTypeSymbol))
-            changeReturnUnitToReturnInstance(newThis)
-
-            statements.add(3, openBoxStatement(newThis.symbol, boxSymbol))
-            statements.add(returnThis(constructor, newThis))
-
-            redirectOldThisToNewOne(constructor, newThis)
-        } else {
-            fillInitializerBox(boxSymbol, constructor)
-
-            val newThis = createThisVariable(createNewSuperCallSecondaryToPrimary(constructor, superCtor, resultTypeSymbol, boxSymbol))
-            changeReturnUnitToReturnInstance(newThis)
-
-            statements.add(returnThis(constructor, newThis))
-
-            redirectOldThisToNewOne(constructor, newThis)
-        }
-    }
-
-    /**
-     * Derived_constructor(.., box, resultType) {
-     *   var currBox = box || {}
-     *   var currResultType = resultType || Derived
-     *   //fill initialization box
-     *
-     *   //1. Base class isInline or isExternal or array/string
-     *   var $this$ = Base_constructor(..)
-     *   Object.assign(this, currBox)
-     *   //body
-     *   return $this$
-     *
-     *   //2. Base class !isInline and !isExternal and !(array/string)
-     *   var $this$ = Base_constructor(.., currBox, currResultType)
-     *   //body
-     *   return $this$
-     * }
-     */
-    private fun secondaryToSecondary(helper: LowerCtorHelper) = with(helper) {
-        statements.add(0, boxOrEmptyObject)
-        statements.add(1, resultTypeOrDefaultType())
-        val resultTypeSymbol = (statements[1] as IrVariable).symbol
-
-        putBoxToSuperCall(boxSymbol, constructor)
-        fillInitializerBox(boxSymbol, constructor)
-
-        if (superCtor.hasStrictSignature()) {
-            val newThis = createThisVariable(superCall)
-            changeReturnUnitToReturnInstance(newThis)
-
-            statements.add(3, openBoxStatement(newThis.symbol, boxSymbol))
-            statements += returnThis(constructor, newThis)
-
-            redirectOldThisToNewOne(constructor, newThis)
-        } else {
-            val newThis = createThisVariable(createNewSuperCallSecondaryToSecondary(superCall, boxSymbol, resultTypeSymbol))
-            changeReturnUnitToReturnInstance(newThis)
-
-            statements += returnThis(constructor, newThis)
-
-            redirectOldThisToNewOne(constructor, newThis)
-        }
-    }
-
-    //superCallBuilder
-    private fun createNewSuperCallSecondaryToSecondary(
-        superCall: IrDelegatingConstructorCall,
-        boxSymbol: IrValueSymbol,
-        resultTypeSymbol: IrVariableSymbol
-    ) = superCall.apply {
-        putValueArgument(ES6_INIT_BOX_PARAMETER, JsIrBuilder.buildGetValue(boxSymbol))
-        putValueArgument(ES6_RESULT_TYPE_PARAMETER, JsIrBuilder.buildGetValue(resultTypeSymbol))
-    }
-
-    //superCallBuilder
-    private fun createNewSuperCallPrimaryToSecondary(
-        superCall: IrDelegatingConstructorCall,
-        newTarget: IrCall? = null
-    ) = superCall.apply { putValueArgument(ES6_RESULT_TYPE_PARAMETER, newTarget) }
-
-    private fun IrDelegatingConstructorCall.putValueArgument(origin: IrDeclarationOrigin, value: IrExpression?) {
-        val valueParameters = symbol.owner.valueParameters
-        for (i in valueParameters.indices) {
-            if (valueParameters[i].origin === origin) {
-                putValueArgument(i, value)
+            factory.body = constructor.body?.deepCopyWithSymbols(factory)?.apply {
+                transformChildrenVoid(ValueRemapper(mapOf(irClass.thisReceiver!!.symbol to factory.extensionReceiverParameter!!.symbol)))
             }
+
+            constructorFactory = factory
         }
     }
 
-    //superCallBuilder
-    private fun createNewSuperCallSecondaryToPrimary(
-        constructor: IrConstructor,
-        superCtor: IrConstructor,
-        resultTypeSymbol: IrVariableSymbol,
-        boxSymbol: IrVariableSymbol? = null
-    ): IrCall {
-        val callType = JsIrBuilder.buildCall(context.intrinsics.jsClass, context.dynamicType, listOf(superCtor.returnType))
-        val resultType = JsIrBuilder.buildGetValue(resultTypeSymbol)
-        val arguments = IrVarargImpl(
-            UNDEFINED_OFFSET, UNDEFINED_OFFSET,
-            context.irBuiltIns.anyNType,
-            context.irBuiltIns.anyNType,
-            getElements(constructor, boxSymbol)
+    private fun IrConstructor.generateCreateFunction(): IrSimpleFunction {
+        val constructor = this
+        val irClass = parentAsClass
+        val type = irClass.defaultType
+        val constructorName = "new_${irClass.constructorPostfix}"
+
+        return context.irFactory.buildFun {
+            name = Name.identifier(constructorName)
+            returnType = type
+            visibility = constructor.visibility
+            modality = Modality.FINAL
+            isInline = constructor.isInline
+            isExternal = constructor.isExternal
+            origin = when {
+                constructor.isPrimary -> ES6_PRIMARY_CONSTRUCTOR_REPLACEMENT
+                else -> ES6_CONSTRUCTOR_REPLACEMENT
+            }
+        }.also { factory ->
+            factory.parent = irClass
+            factory.copyTypeParametersFrom(irClass)
+            factory.copyValueParametersFrom(constructor)
+            factory.annotations = annotations
+            factory.dispatchReceiverParameter = irClass.thisReceiver?.copyTo(factory)
+
+            if (irClass.isExported(context) && constructor.isPrimary) {
+                factory.excludeFromExport()
+            }
+
+            factory.body = context.irFactory.createBlockBody(UNDEFINED_OFFSET, UNDEFINED_OFFSET) {
+                val bodyCopy = constructor.body?.deepCopyWithSymbols(factory) ?: return@createBlockBody
+                val self = bodyCopy.replaceSuperCallsAndThisUsages(irClass, factory, constructor)
+                statements.addAll(bodyCopy.statements)
+                statements.add(JsIrBuilder.buildReturn(factory.symbol, JsIrBuilder.buildGetValue(self), irClass.defaultType))
+            }
+
+            constructorFactory = factory
+        }
+    }
+
+    private fun IrFunction.generateThisVariable(irClass: IrClass, initializer: IrExpression): IrVariable {
+        return JsIrBuilder.buildVar(
+            type = irClass.defaultType,
+            parent = this,
+            name = Namer.SYNTHETIC_RECEIVER_NAME,
+            initializer = initializer
         )
-
-        if (superCtor.parentAsClass.defaultType.isAny()) {
-            //superType is Any, and we have default primary --> create call to default primary
-            return JsIrBuilder.buildCall(context.intrinsics.jsConstruct, context.irBuiltIns.nothingType).apply {
-                arguments.elements.clear()
-                arguments.addElement(JsIrBuilder.buildGetValue(boxSymbol!!))
-
-                putValueArgument(0, JsIrBuilder.buildCall(context.intrinsics.jsClass, context.dynamicType, listOf(constructor.returnType)))
-                putValueArgument(1, resultType)
-                putValueArgument(2, arguments)
-
-                putTypeArgument(0, constructor.returnType)
-            }
-        }
-
-        return JsIrBuilder.buildCall(context.intrinsics.jsConstruct, context.irBuiltIns.nothingType).apply {
-            putValueArgument(0, callType)
-            putValueArgument(1, resultType)
-            putValueArgument(2, arguments)
-
-            putTypeArgument(0, superCtor.returnType)
-        }
     }
 
-    /**
-     * Copy arguments from superCall
-     */
-    private fun getElements(constructor: IrConstructor, boxSymbol: IrValueSymbol? = null): List<IrVarargElement> {
-        val result = mutableListOf<IrVarargElement>()
+    private val IrClass.constructorPostfix: String
+        get() = fqNameWhenAvailable?.asString()?.replace('.', '_') ?: name.toString()
 
-        val superCall = constructor.body!!.statements.filterIsInstance<IrDelegatingConstructorCall>().first()
-        repeat(superCall.valueArgumentsCount) { i ->
-            val arg = superCall.getValueArgument(i) ?: return@repeat
-            if (superCall.symbol.owner.valueParameters[i].origin === ES6_INIT_BOX_PARAMETER) {
-                result += JsIrBuilder.buildGetValue(boxSymbol!!)
-            } else {
-                if (context.inlineClassesUtils.getInlinedClass(arg.type) != null) {
-                    val any = context.irBuiltIns.anyNType
-                    result += JsIrBuilder.buildTypeOperator(any, IrTypeOperator.REINTERPRET_CAST, arg, any)
+    private fun irAnyArray(elements: List<IrExpression>): IrExpression {
+        return JsIrBuilder.buildArray(
+            elements,
+            context.irBuiltIns.arrayClass.typeWith(context.irBuiltIns.anyNType),
+            context.irBuiltIns.anyNType,
+        )
+    }
+
+    private fun IrBody.replaceSuperCallsAndThisUsages(
+        irClass: IrClass,
+        constructorReplacement: IrSimpleFunction,
+        currentConstructor: IrConstructor,
+    ): IrValueSymbol {
+        var generatedThisValueSymbol: IrValueSymbol? = null
+        val selfParameterSymbol = irClass.thisReceiver!!.symbol
+        val boxParameterSymbol = constructorReplacement.boxParameter
+
+        transformChildrenVoid(object : ValueRemapper(emptyMap()) {
+            override val map: MutableMap<IrValueSymbol, IrValueSymbol> = currentConstructor.valueParameters
+                .zip(constructorReplacement.valueParameters)
+                .associate { it.first.symbol to it.second.symbol }
+                .toMutableMap()
+
+            override fun visitReturn(expression: IrReturn): IrExpression {
+                return if (expression.returnTargetSymbol == currentConstructor.symbol) {
+                    super.visitReturn(
+                        JsIrBuilder.buildReturn(
+                            constructorReplacement.symbol,
+                            JsIrBuilder.buildGetValue(selfParameterSymbol),
+                            irClass.defaultType
+                        )
+                    )
                 } else {
-                    result += arg
-                }
-            }
-        }
-
-        return result
-    }
-
-    //builder
-    private fun returnThis(constructor: IrConstructor, newThis: IrVariable): IrReturn {
-        return JsIrBuilder.buildReturn(
-            constructor.symbol,
-            JsIrBuilder.buildGetValue(newThis.symbol),
-            context.irBuiltIns.nothingType
-        )
-    }
-
-    /**
-     * Transform statements like `this.x = y` to `box.x = y`
-     */
-    private fun fillInitializerBox(boxSymbol: IrValueSymbol, constructor: IrConstructor) {
-        val statements = (constructor.body as IrBlockBody).statements
-        for (i in statements.indices) {
-            val current = statements[i]
-            if (current is IrSetField) {
-                if ((current.receiver as? IrGetValue)?.symbol?.owner === constructor.parentAsClass.thisReceiver) {
-                    current.receiver = JsIrBuilder.buildGetValue(boxSymbol)
+                    super.visitReturn(expression)
                 }
             }
 
-            if (statements[i] is IrDelegatingConstructorCall) {
-                break
-            }
-        }
-    }
-
-    //transformer
-    private fun putBoxToSuperCall(boxSymbol: IrValueSymbol, constructor: IrConstructor) {
-        constructor.transformChildren(object : IrElementTransformerVoid() {
             override fun visitDelegatingConstructorCall(expression: IrDelegatingConstructorCall): IrExpression {
-                return expression.also { it.putValueArgument(ES6_INIT_BOX_PARAMETER, JsIrBuilder.buildGetValue(boxSymbol)) }
+                val constructor = expression.symbol.owner
+
+                if (constructor.isSyntheticPrimaryConstructor) {
+                    return JsIrBuilder.buildConstructorCall(expression.symbol, origin = ES6_INIT_CALL)
+                        .apply {
+                            copyValueArgumentsFrom(expression, constructor)
+                            extensionReceiver = JsIrBuilder.buildGetValue(selfParameterSymbol)
+                        }
+                        .run { visitConstructorCall(this) }
+                }
+
+                val boxParameterGetter = boxParameterSymbol?.let { JsIrBuilder.buildGetValue(it.symbol) } ?: context.getVoid()
+
+                val newThisValue = when {
+                    constructor.isEffectivelyExternal() ->
+                        JsIrBuilder.buildCall(context.intrinsics.jsCreateExternalThisSymbol)
+                            .apply {
+                                putValueArgument(0, irClass.getCurrentConstructorReference(constructorReplacement))
+                                putValueArgument(1, expression.symbol.owner.parentAsClass.jsConstructorReference(context))
+                                putValueArgument(2, irAnyArray(expression.valueArguments.map { it ?: context.getVoid() }))
+                                putValueArgument(3, boxParameterGetter)
+                            }
+                    constructor.parentAsClass.symbol == context.irBuiltIns.anyClass ->
+                        JsIrBuilder.buildCall(context.intrinsics.jsCreateThisSymbol)
+                            .apply {
+                                putValueArgument(0, irClass.getCurrentConstructorReference(constructorReplacement))
+                                putValueArgument(1, boxParameterGetter)
+                            }
+                    else ->
+                        JsIrBuilder.buildConstructorCall(
+                            expression.symbol,
+                            null,
+                            expression.typeArguments,
+                            ES6_DELEGATING_CONSTRUCTOR_REPLACEMENT
+                        ).apply {
+                            copyValueArgumentsFrom(expression, constructor)
+                        }
+                }
+
+                val newThisVariable = constructorReplacement.generateThisVariable(irClass, newThisValue)
+                    .also {
+                        generatedThisValueSymbol = it.symbol
+                        map[selfParameterSymbol] = it.symbol
+                    }
+
+                return super.visitComposite(JsIrBuilder.buildComposite(context.irBuiltIns.unitType, listOf(newThisVariable)))
             }
-        }, null)
+        })
+
+        return generatedThisValueSymbol!!
     }
 
-    //builder
-    private fun openBoxStatement(thisSymbol: IrValueSymbol, boxSymbol: IrValueSymbol): IrCall {
-        return JsIrBuilder.buildCall(context.intrinsics.jsOpenInitializerBox).also {
-            it.putValueArgument(0, JsIrBuilder.buildGetValue(thisSymbol))
-            it.putValueArgument(1, JsIrBuilder.buildGetValue(boxSymbol))
+    private fun IrClass.getCurrentConstructorReference(currentFactoryFunction: IrSimpleFunction): IrExpression {
+        return if (isFinalClass) {
+            jsConstructorReference(context)
+        } else {
+            JsIrBuilder.buildGetValue(currentFactoryFunction.dispatchReceiverParameter!!.symbol)
         }
     }
 
-    //util
-    private fun IrConstructor.hasStrictSignature(): Boolean {
-        val primitives = with(context.irBuiltIns) { primitiveTypesToPrimitiveArrays.values + stringClass }
-        return with(parentAsClass) { isExternal || context.inlineClassesUtils.isClassInlineLike(this) || symbol in primitives }
+    private fun IrDeclaration.excludeFromExport() {
+        val jsExportIgnoreClass = context.intrinsics.jsExportIgnoreAnnotationSymbol.owner
+        val jsExportIgnoreCtor = jsExportIgnoreClass.primaryConstructor ?: return
+        annotations += JsIrBuilder.buildConstructorCall(jsExportIgnoreCtor.symbol)
     }
 }
-
-//transformer
-private fun replaceCallToDefaultPrimary(context: JsIrBackendContext, constructor: IrConstructor) {
-    val thisSymbol = (((constructor.body as IrBlockBody).statements
-        .find { it is IrVariable && it.origin === ES6_THIS_VARIABLE_ORIGIN }) as IrVariable?)?.symbol ?: return
-
-    (constructor.body as IrBlockBody).statements.transformInPlace {
-        if (it is IrDelegatingConstructorCall) {
-            val superCtor = it.symbol.owner
-            val initFunc = context.mapping.constructorToInitFunction[superCtor]!!
-
-            JsIrBuilder.buildCall(initFunc.symbol).apply {
-                putValueArgument(0, JsIrBuilder.buildGetValue(thisSymbol))
-            }
-        } else it
-    }
-}
-
-//transformer
-private fun redirectOldThisToNewOne(constructor: IrConstructor, newThis: IrVariable) {
-    constructor.transformChildren(object : IrElementTransformerVoid() {
-        override fun visitGetValue(expression: IrGetValue): IrExpression {
-            return if (expression.symbol.owner === constructor.parentAsClass.thisReceiver!!) {
-                with(expression) { IrGetValueImpl(startOffset, endOffset, type, newThis.symbol) }
-            } else {
-                expression
-            }
-        }
-    }, null)
-}
-
-/**
- * Change `return Unit` to `return $this$`
- */
-private fun LowerCtorHelper.changeReturnUnitToReturnInstance(newThis: IrVariable) {
-    constructor.transformChildren(object : IrElementTransformerVoid() {
-        override fun visitReturn(expression: IrReturn): IrExpression {
-            return JsIrBuilder.buildReturn(
-                constructor.symbol,
-                JsIrBuilder.buildGetValue(newThis.symbol),
-                expression.type
-            )
-        }
-    }, null)
-}
-
-private fun hackEnums(constructor: IrConstructor) {
-    constructor.transformChildren(object : IrElementTransformerVoid() {
-        override fun visitTypeOperator(expression: IrTypeOperatorCall): IrExpression {
-            return (expression.argument as? IrDelegatingConstructorCall) ?: expression
-        }
-    }, null)
-}
-
-/**
- * Swap call synthetic primary ctor and call extendThrowable
- */
-private fun hackExceptions(context: JsIrBackendContext, constructor: IrConstructor) {
-    val setPropertiesSymbol = context.setPropertiesToThrowableInstanceSymbol
-
-    val statements = (constructor.body as IrBlockBody).statements
-
-    var callIndex = -1
-    var superCallIndex = -1
-    for (i in statements.indices) {
-        val s = statements[i]
-
-        if (s is IrCall && s.symbol === setPropertiesSymbol) callIndex = i
-        if (s is IrDelegatingConstructorCall && s.symbol.owner.origin === SYNTHETIC_PRIMARY_CONSTRUCTOR) superCallIndex = i
-    }
-
-    if (callIndex != -1 && superCallIndex != -1) {
-        val tmp = statements[callIndex]
-        statements[callIndex] = statements[superCallIndex]
-        statements[superCallIndex] = tmp
-    }
-}
-
-private class LowerCtorHelper(
-    private val context: JsIrBackendContext,
-    val constructor: IrConstructor,
-    val superCtor: IrConstructor
-) {
-    private val boxParameterSymbol = constructor.valueParameters.find { it.origin === ES6_INIT_BOX_PARAMETER }!!.symbol
-    val resultTypeParameterSymbol by lazy {
-        constructor.valueParameters.find { it.origin === ES6_RESULT_TYPE_PARAMETER }!!.symbol
-    }
-
-    val statements = (constructor.body as IrBlockBody).statements
-
-    /**
-     * var currBox = box || {}
-     */
-    val boxOrEmptyObject = boxOrEmptyObject(boxParameterSymbol, constructor)
-    private fun boxOrEmptyObject(boxSymbol: IrValueSymbol, parent: IrConstructor): IrVariable {
-        val emptyObject = JsIrBuilder.buildCall(context.intrinsics.jsEmptyObject)
-        val or = JsIrBuilder.buildCall(context.intrinsics.jsOr, context.dynamicType).apply {
-            putValueArgument(0, JsIrBuilder.buildGetValue(boxSymbol))
-            putValueArgument(1, emptyObject)
-        }
-        return JsIrBuilder.buildVar(context.dynamicType, parent, "currBox", initializer = or)
-    }
-
-    val boxSymbol = boxOrEmptyObject.symbol
-    val thisSymbol = constructor.parentAsClass.thisReceiver!!.symbol
-
-    val superCall: IrDelegatingConstructorCall by lazy { getSuperCall(constructor)!! }
-
-    /**
-     * var $this$ = `newSuperCall`
-     */
-    fun createThisVariable(newSuperCall: IrExpression): IrVariable {
-        val newThis = JsIrBuilder.buildVar(
-            context.dynamicType,
-            constructor,
-            "\$this\$",
-            initializer = newSuperCall
-        ).apply {
-            origin = ES6_THIS_VARIABLE_ORIGIN
-        }
-
-        (constructor.body as IrBlockBody).statements.transformInPlace {
-            if (it === superCall) newThis
-            else it
-        }
-
-        return newThis
-    }
-
-    /**
-     * var currResultType = resultType || D
-     */
-    fun resultTypeOrDefaultType(): IrStatement {
-        val defaultType = JsIrBuilder.buildCall(context.intrinsics.es6DefaultType).apply {
-            putTypeArgument(0, constructor.parentAsClass.defaultType)
-        }
-        val or = JsIrBuilder.buildCall(context.intrinsics.jsOr, context.dynamicType).apply {
-            putValueArgument(0, JsIrBuilder.buildGetValue(resultTypeParameterSymbol))
-            putValueArgument(1, defaultType)
-        }
-        return JsIrBuilder.buildVar(context.dynamicType, constructor, "currResultType", initializer = or)
-    }
-}
-
-private fun getSuperCall(constructor: IrConstructor): IrDelegatingConstructorCall? {
-    var result: IrDelegatingConstructorCall? = null
-    (constructor.body as IrBlockBody).acceptChildren(object : IrElementVisitor<Unit, Any?> {
-        override fun visitElement(element: IrElement, data: Any?) { }
-
-        override fun visitBlock(expression: IrBlock, data: Any?) {
-            expression.statements.forEach { it.accept(this, data) }
-        }
-
-        override fun visitDelegatingConstructorCall(expression: IrDelegatingConstructorCall, data: Any?) {
-            result = result ?: expression
-        }
-    }, null)
-    return result
-}
-
-private fun changeIrConstructorToIrFunction(context: JsIrBackendContext, container: IrConstructor) {
-    val newConstructor = context.irFactory.buildFun {
-        name = Name.identifier("${container.parentAsClass.name}_constructor")
-        returnType = container.returnType
-        origin = JsIrBuilder.SYNTHESIZED_DECLARATION
-    }.apply {
-        parent = container.parent
-        container.valueParameters.forEach { param ->
-            addValueParameter(param.name.asString(), param.type, param.origin)
-        }
-
-        val parametersMap = container.valueParameters.zip(valueParameters).toMap()
-        body = container.body
-        transformChildren(object : IrElementTransformerVoid() {
-            override fun visitGetValue(expression: IrGetValue): IrExpression {
-                val newParam = parametersMap[expression.symbol.owner]
-                return if (newParam != null) JsIrBuilder.buildGetValue(newParam.symbol) else expression
-            }
-        }, null)
-    }
-
-    container.parentAsClass.declarations.transformInPlace {
-        if (it === container) newConstructor else it
-    }
-
-    context.mapping.secondaryConstructorToDelegate[container] = newConstructor
-}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ES6PrimaryConstructorOptimizationLowering.kt

@@ -0,0 +1,258 @@
+/*
+ * Copyright 2010-2020 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.ir.backend.js.lower
+
+import org.jetbrains.kotlin.backend.common.BodyLoweringPass
+import org.jetbrains.kotlin.backend.common.DeclarationTransformer
+import org.jetbrains.kotlin.backend.common.ir.ValueRemapper
+import org.jetbrains.kotlin.ir.IrStatement
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.export.isExported
+import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
+import org.jetbrains.kotlin.ir.backend.js.utils.JsAnnotations
+import org.jetbrains.kotlin.ir.backend.js.utils.MutableReference
+import org.jetbrains.kotlin.ir.backend.js.utils.irEmpty
+import org.jetbrains.kotlin.ir.backend.js.utils.mutableReferenceOf
+import org.jetbrains.kotlin.ir.builders.declarations.buildConstructor
+import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.symbols.IrValueSymbol
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
+import org.jetbrains.kotlin.util.collectionUtils.filterIsInstanceAnd
+
+const val CREATE_EXTERNAL_THIS_CONSTRUCTOR_PARAMETERS = 2
+
+class ES6PrimaryConstructorOptimizationLowering(private val context: JsIrBackendContext) : DeclarationTransformer {
+    override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
+        if (!context.es6mode || declaration !is IrFunction || !declaration.shouldBeConvertedToPlainConstructor(context)) {
+            return null
+        }
+
+        val irClass = declaration.parentAsClass
+
+        if (irClass.isExported(context)) {
+            irClass.removeConstructorForExport()
+        }
+
+        return listOf(declaration.convertToRegularConstructor(irClass))
+    }
+
+    private fun IrFunction.convertToRegularConstructor(irClass: IrClass): IrConstructor {
+        val original = this
+        val superClass = irClass.superClass
+        val classThisSymbol = irClass.thisReceiver!!.symbol
+
+        return factory.buildConstructor {
+            updateFrom(original)
+            isPrimary = true
+            returnType = original.returnType
+            origin = IrDeclarationOrigin.DEFINED
+        }.also { constructor ->
+            constructor.copyAnnotationsFrom(original)
+            constructor.copyParameterDeclarationsFrom(original)
+            constructor.parent = irClass
+
+            if (irClass.isExported(context)) {
+                constructor.annotations = original.annotations.withoutFirst { it.isAnnotation(JsAnnotations.jsExportIgnoreFqn) }
+            }
+
+            val boxParameter = constructor.boxParameter
+            val body = (original.body?.deepCopyWithSymbols(constructor) as IrBlockBody)
+                .also { constructor.body = it }
+
+            body.transformChildrenVoid(object : ValueRemapper(emptyMap()) {
+                override val map = original.valueParameters.zip(constructor.valueParameters)
+                    .associate { it.first.symbol to it.second.symbol }
+                    .toMutableMap<IrValueSymbol, IrValueSymbol>()
+
+                override fun visitReturn(expression: IrReturn): IrExpression {
+                    return if (expression.returnTargetSymbol == original.symbol) {
+                        return irEmpty(context)
+                    } else {
+                        super.visitReturn(expression)
+                    }
+                }
+
+                override fun visitCall(expression: IrCall): IrExpression {
+                    return if (expression.symbol == context.intrinsics.jsBoxApplySymbol) {
+                        irEmpty(context)
+                    } else {
+                        super.visitCall(expression)
+                    }
+                }
+
+                override fun visitVariable(declaration: IrVariable): IrStatement {
+                    val initializer = declaration.initializer
+
+                    if (initializer is IrCall) {
+                        when {
+                            initializer.isSyntheticDelegatingReplacement -> {
+                                map[declaration.symbol] = classThisSymbol
+                                return super.visitCall(initializer)
+                            }
+                            initializer.symbol == context.intrinsics.jsCreateThisSymbol -> {
+                                map[declaration.symbol] = classThisSymbol
+
+                                return if (boxParameter != null && superClass == null) {
+                                    super.visitCall(JsIrBuilder.buildCall(context.intrinsics.jsBoxApplySymbol).apply {
+                                        putValueArgument(0, JsIrBuilder.buildGetValue(irClass.thisReceiver!!.symbol))
+                                        putValueArgument(1, JsIrBuilder.buildGetValue(boxParameter.symbol))
+                                    })
+                                } else {
+                                    irEmpty(context)
+                                }
+                            }
+                            initializer.symbol == context.intrinsics.jsCreateExternalThisSymbol -> {
+                                map[declaration.symbol] = classThisSymbol
+
+                                val externalConstructor =
+                                    superClass?.primaryConstructor?.symbol ?: error("Expect to have external constructor here")
+                                val parameters = initializer.getValueArgument(CREATE_EXTERNAL_THIS_CONSTRUCTOR_PARAMETERS) as? IrVararg
+                                    ?: error("Wrong type of argument was provided")
+
+                                return JsIrBuilder.buildDelegatingConstructorCall(externalConstructor).apply {
+                                    parameters.elements.forEachIndexed { i, it -> putValueArgument(i, it as IrExpression) }
+                                }
+                            }
+                        }
+                    }
+
+                    return super.visitVariable(declaration)
+                }
+            })
+        }
+    }
+
+    private fun IrClass.removeConstructorForExport() {
+        declarations.removeIf { it is IrConstructor }
+    }
+
+    private inline fun <T> Iterable<T>.withoutFirst(predicate: (T) -> Boolean): List<T> {
+        val original = this
+        return buildList {
+            var isFirstMatch = true
+            for (element in original) {
+                if (!isFirstMatch || !predicate(element)) {
+                    add(element)
+                } else {
+                    isFirstMatch = false
+                }
+            }
+        }
+    }
+}
+
+class ES6PrimaryConstructorUsageOptimizationLowering(private val context: JsIrBackendContext) : BodyLoweringPass {
+    override fun lower(irBody: IrBody, container: IrDeclaration) {
+        irBody.transformChildrenVoid(object : IrElementTransformerVoid() {
+            override fun visitCall(expression: IrCall): IrExpression {
+                val callee = expression.symbol.owner
+                return when {
+                    !callee.shouldBeConvertedToPlainConstructor(context) -> super.visitCall(expression)
+                    expression.isSyntheticDelegatingReplacement -> {
+                        super.visitDelegatingConstructorCall(JsIrBuilder.buildDelegatingConstructorCall(callee.parentAsClass.primaryConstructor!!.symbol)
+                                                                 .apply { copyTypeAndValueArgumentsFrom(expression) })
+                    }
+                    else -> {
+                        super.visitConstructorCall(JsIrBuilder.buildConstructorCall(callee.parentAsClass.primaryConstructor!!.symbol)
+                                                       .apply { copyTypeAndValueArgumentsFrom(expression) })
+                    }
+                }
+            }
+        })
+    }
+}
+
+/**
+ * When we can't optimize class hierarchy chain if there is a class inside which:
+ * 1. Has primary constructor which delegates to a secondary
+ * 2. Has secondary constructor which delegates to a primary
+ * 3. Has a constructor with a box parameter, and it has an external superclass
+ * 4. Is a subtype for Throwable, because we replace the super call inside constructors with `setPropertiesToThrowableInstance` call
+ * Otherwise, we can generate a simple ES-class constructor in each class of the hierarchy
+ */
+class ES6CollectPrimaryConstructorsWhichCouldBeOptimizedLowering(private val context: JsIrBackendContext) : DeclarationTransformer {
+    private val esClassWhichNeedBoxParameters = context.mapping.esClassWhichNeedBoxParameters
+    private val esClassToPossibilityForOptimization = context.mapping.esClassToPossibilityForOptimization
+
+    override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
+        if (
+            context.es6mode &&
+            declaration is IrClass &&
+            !declaration.isExternal &&
+            !context.inlineClassesUtils.isClassInlineLike(declaration) &&
+            !esClassToPossibilityForOptimization.contains(declaration)
+        ) {
+            declaration.checkIfCanBeOptimized()
+        }
+
+        return null
+    }
+
+    private fun IrClass.checkIfCanBeOptimized() {
+        var currentClass: IrClass? = this
+        var nearestOptimizationDecision: MutableReference<Boolean>? = null
+
+        while (currentClass != null && !currentClass.isExternal) {
+            val currentClassOptimizationDecision = esClassToPossibilityForOptimization[currentClass]
+
+            if (currentClassOptimizationDecision != null) {
+                nearestOptimizationDecision = currentClassOptimizationDecision
+                break
+            }
+
+            currentClass = currentClass.superClass
+        }
+
+        if (nearestOptimizationDecision == null) {
+            nearestOptimizationDecision = mutableReferenceOf(true)
+        }
+
+        currentClass = this
+        while (currentClass != null && !currentClass.isExternal && !esClassToPossibilityForOptimization.contains(currentClass)) {
+            esClassToPossibilityForOptimization[currentClass] = nearestOptimizationDecision
+
+            if (nearestOptimizationDecision.value && !currentClass.canBeOptimized()) {
+                nearestOptimizationDecision.value = false
+            }
+
+            currentClass = currentClass.superClass
+        }
+    }
+
+    private fun IrClass.canBeOptimized(): Boolean {
+        return superClass?.symbol != context.throwableClass && !isSubclassOfExternalClassWithRequiredBoxParameter() && !hasPrimaryDelegatedToSecondaryOrSecondaryToPrimary()
+    }
+
+    private fun IrClass.hasPrimaryDelegatedToSecondaryOrSecondaryToPrimary(): Boolean {
+        declarations
+            .filterIsInstanceAnd<IrFunction> { it.isEs6ConstructorReplacement }
+            .forEach {
+                var meetUnoptimizedDelegation = false
+                it.body?.transformChildrenVoid(object : IrElementTransformerVoid() {
+                    override fun visitCall(expression: IrCall): IrExpression {
+                        if (expression.isSyntheticDelegatingReplacement && expression.symbol.owner.origin != it.origin) {
+                            meetUnoptimizedDelegation = true
+                        }
+                        return super.visitCall(expression)
+                    }
+                })
+
+                if (meetUnoptimizedDelegation) return true
+            }
+        return false
+    }
+
+    private fun IrClass.isSubclassOfExternalClassWithRequiredBoxParameter(): Boolean {
+        return superClass?.isExternal == true && esClassWhichNeedBoxParameters.contains(this)
+    }
+}
+
+private fun IrFunction.shouldBeConvertedToPlainConstructor(context: JsIrBackendContext): Boolean {
+    return isEs6PrimaryConstructorReplacement && context.mapping.esClassToPossibilityForOptimization[parentAsClass]?.value == true
+}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ImplicitlyExportedDeclarationsMarkingLowering.kt

@@ -6,11 +6,10 @@
 package org.jetbrains.kotlin.ir.backend.js.lower
 
 import org.jetbrains.kotlin.backend.common.DeclarationTransformer
-import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.export.isExported
+import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
 import org.jetbrains.kotlin.ir.backend.js.utils.isJsImplicitExport
-import org.jetbrains.kotlin.ir.builders.irCall
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
@@ -86,7 +85,7 @@ class ImplicitlyExportedDeclarationsMarkingLowering(private val context: JsIrBac
 
     private fun IrDeclaration.markWithJsImplicitExport() {
         val jsImplicitExportCtor = context.intrinsics.jsImplicitExportAnnotationSymbol.constructors.single()
-        annotations += context.createIrBuilder(symbol).irCall(jsImplicitExportCtor)
+        annotations += JsIrBuilder.buildConstructorCall(jsImplicitExportCtor)
 
         parentClassOrNull?.takeIf { it.shouldBeMarkedWithImplicitExport() }?.markWithJsImplicitExport()
     }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsClassUsageInReflectionLowering.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.JsStatementOrigins
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
+import org.jetbrains.kotlin.ir.backend.js.utils.jsConstructorReference
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
@@ -44,7 +45,7 @@ class JsClassUsageInReflectionLowering(val backendContext: JsIrBackendContext) :
 
     private fun IrClassReference.generateDirectValueUsage(): IrExpression? {
         return with(backendContext) {
-            when(val classSymbol = symbol as? IrClassSymbol ?: return null) {
+            when (val classSymbol = symbol as? IrClassSymbol ?: return null) {
                 irBuiltIns.nothingClass -> null
                 irBuiltIns.anyClass ->
                     JsIrBuilder.buildCall(intrinsics.jsCode).apply {
@@ -59,10 +60,7 @@ class JsClassUsageInReflectionLowering(val backendContext: JsIrBackendContext) :
                         )
                     }
 
-                else ->
-                    JsIrBuilder.buildCall(intrinsics.jsClass, origin = JsStatementOrigins.CLASS_REFERENCE).apply {
-                        putTypeArgument(0, classSymbol.owner.defaultType)
-                    }
+                else -> classSymbol.owner.jsConstructorReference(backendContext)
             }
         }
     }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsDefaultArgumentStubGenerator.kt

@@ -17,13 +17,11 @@ import org.jetbrains.kotlin.ir.backend.js.utils.JsAnnotations
 import org.jetbrains.kotlin.ir.backend.js.utils.getVoid
 import org.jetbrains.kotlin.ir.backend.js.utils.realOverrideTarget
 import org.jetbrains.kotlin.ir.builders.*
-import org.jetbrains.kotlin.ir.builders.declarations.addValueParameter
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.utils.addIfNotNull
 import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
@@ -72,18 +70,13 @@ class JsDefaultArgumentStubGenerator(override val context: JsIrBackendContext) :
                 ?.also { new -> variables[param] = new } ?: param
         }
 
-        val defaultResolutionStatements = valueParameters.mapNotNull {
-            irBuilder.createResolutionStatement(it, it.defaultValue?.expression)
-        }
-
-        if (variables.isNotEmpty()) {
-            body?.transformChildren(VariableRemapper(variables), null)
-
-            body = context.irFactory.createBlockBody(UNDEFINED_OFFSET, UNDEFINED_OFFSET) {
-                statements += defaultResolutionStatements
-                statements += body?.statements ?: emptyList()
-            }
+        val blockBody = body as? IrBlockBody
 
+        if (blockBody != null && variables.isNotEmpty()) {
+            blockBody.transformChildren(VariableRemapper(variables), null)
+            blockBody.statements.addAll(0, valueParameters.mapNotNull {
+                irBuilder.createResolutionStatement(it, it.defaultValue?.expression)
+            })
         }
 
         return also {

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsDefaultParameterInjector.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
 import org.jetbrains.kotlin.ir.backend.js.JsStatementOrigins
 import org.jetbrains.kotlin.ir.backend.js.export.isExported
 import org.jetbrains.kotlin.ir.backend.js.utils.getVoid
+import org.jetbrains.kotlin.ir.backend.js.utils.jsConstructorReference
 import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.declarations.IrValueParameter
 import org.jetbrains.kotlin.ir.expressions.IrCall
@@ -91,19 +92,7 @@ class JsDefaultParameterInjector(override val context: JsIrBackendContext) :
             0,
             1
         ).apply {
-            putValueArgument(
-                0,
-                IrCallImpl(
-                    UNDEFINED_OFFSET,
-                    UNDEFINED_OFFSET,
-                    context.dynamicType,
-                    context.intrinsics.jsClass,
-                    1,
-                    0
-                ).apply {
-                    putTypeArgument(0, owner.defaultType)
-                }
-            )
+            putValueArgument(0, owner.jsConstructorReference(context))
         }
     }
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsInnerClassesSupport.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.backend.common.lower.InnerClassesSupport
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
 import org.jetbrains.kotlin.ir.backend.js.JsMapping
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder.SYNTHESIZED_DECLARATION
+import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
 import org.jetbrains.kotlin.ir.backend.js.utils.Namer
 import org.jetbrains.kotlin.ir.builders.declarations.buildConstructor
 import org.jetbrains.kotlin.ir.builders.declarations.buildField
@@ -41,7 +42,7 @@ class JsInnerClassesSupport(mapping: JsMapping, private val irFactory: IrFactory
 
                 irFactory.buildField {
                     origin = IrDeclarationOrigin.FIELD_FOR_OUTER_THIS
-                    name = Name.identifier("\$this")
+                    name = Name.identifier(Namer.SYNTHETIC_RECEIVER_NAME)
                     type = outerClass.defaultType
                     visibility = DescriptorVisibilities.PROTECTED
                     isFinal = true

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ObjectLowering.kt

@@ -12,15 +12,19 @@ import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.irBlockBody
 import org.jetbrains.kotlin.backend.common.lower.irIfThen
 import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsCommonBackendContext
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
 import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
+import org.jetbrains.kotlin.ir.backend.js.utils.getVoid
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.builders.declarations.buildField
 import org.jetbrains.kotlin.ir.builders.declarations.buildFun
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.symbols.IrFieldSymbol
 import org.jetbrains.kotlin.ir.types.makeNullable
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
@@ -28,9 +32,7 @@ import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
-class ObjectDeclarationLowering(
-    val context: JsCommonBackendContext
-) : DeclarationTransformer {
+class ObjectDeclarationLowering(val context: JsCommonBackendContext) : DeclarationTransformer {
 
     private var IrClass.instanceField by context.mapping.objectToInstanceField
     private var IrClass.syntheticPrimaryConstructor by context.mapping.classToSyntheticPrimaryConstructor
@@ -39,7 +41,6 @@ class ObjectDeclarationLowering(
      * If the object being lowered is nested inside an enum class, we want to also initialize the enum entries when initializing the object.
      */
     private var IrClass.initEntryInstancesFun: IrSimpleFunction? by context.mapping.enumClassToInitEntryInstancesFun
-
     override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
         if (declaration !is IrClass || declaration.kind != ClassKind.OBJECT || declaration.isEffectivelyExternal())
             return null
@@ -67,7 +68,7 @@ class ObjectDeclarationLowering(
                 if (initEntryInstancesFun != null)
                     +irCall(initEntryInstancesFun)
                 +irIfThen(
-                    irEqualsNull(irGetField(null, instanceField)),
+                    irNullabilityCheck(instanceField),
                     // Instance field initialized inside constructor
                     irCallConstructor(primaryConstructor.symbol, emptyList())
                 )
@@ -77,35 +78,30 @@ class ObjectDeclarationLowering(
 
         return listOf(declaration, instanceField, getInstanceFun)
     }
+
+    private fun IrBuilderWithScope.irNullabilityCheck(instanceField: IrField): IrExpression {
+        val context = this@ObjectDeclarationLowering.context
+        return if (context is JsIrBackendContext && context.es6mode) {
+            irEqeqeqWithoutBox(irGetField(null, instanceField), context.getVoid())
+        } else {
+            irEqualsNull(irGetField(null, instanceField))
+        }
+    }
 }
 
-class ObjectUsageLowering(
-    val context: JsCommonBackendContext
-) : BodyLoweringPass {
+class ObjectUsageLowering(val context: JsCommonBackendContext) : BodyLoweringPass {
 
     private var IrClass.instanceField by context.mapping.objectToInstanceField
 
     override fun lower(irBody: IrBody, container: IrDeclaration) {
-        if (container is IrConstructor && container.isPrimary) {
-            val irClass = container.parentAsClass
-            irClass.instanceField?.let { instanceField ->
-                // Initialize instance field in the beginning of the constructor because it can be used inside the constructor later
-                val initInstanceField = context.createIrBuilder(container.symbol).buildStatement(UNDEFINED_OFFSET, UNDEFINED_OFFSET) {
-                    irSetField(null, instanceField, irGet(irClass.thisReceiver!!))
-                }
-                if (context.es6mode) {
-                    //find `superCall` and put after
-                    (irBody as IrBlockBody).statements.transformFlat {
-                        if (it is IrDelegatingConstructorCall) listOf(it, initInstanceField)
-                        else if (it is IrVariable && it.origin === ES6_THIS_VARIABLE_ORIGIN) {
-                            initInstanceField.value = JsIrBuilder.buildGetValue(it.symbol)
-                            listOf(it, initInstanceField)
-                        } else null
-                    }
-                } else {
-                    (irBody as IrBlockBody).statements.add(0, initInstanceField)
-                }
-            }
+        val functionContainer = container.takeIf { it is IrConstructor && it.isPrimary }
+        val irClass = functionContainer?.parentAsClass
+
+        irClass?.instanceField?.let {
+            if (context.es6mode && irClass.superClass == null) return@let
+            // Initialize instance field in the beginning of the constructor because it can be used inside the constructor later
+            val initInstanceField = generateInitInstanceField(it, irClass.getValueForInstanceFieldForTheFirstTime())
+            (irBody as IrBlockBody).statements.add(0, initInstanceField)
         }
 
         irBody.transformChildrenVoid(object : IrElementTransformerVoid() {
@@ -114,8 +110,35 @@ class ObjectUsageLowering(
                 if (obj.isEffectivelyExternal()) return expression
                 return JsIrBuilder.buildCall(context.getOrCreateGetInstanceFunction(obj).symbol)
             }
+
+            override fun visitDelegatingConstructorCall(expression: IrDelegatingConstructorCall): IrExpression {
+                val instanceField = irClass?.instanceField
+                return if (!context.es6mode || instanceField == null) {
+                    super.visitDelegatingConstructorCall(expression)
+                } else {
+                    JsIrBuilder.buildComposite(
+                        context.irBuiltIns.unitType,
+                        listOf(
+                            super.visitDelegatingConstructorCall(expression),
+                            generateInitInstanceField(instanceField, JsIrBuilder.buildGetValue(irClass.thisReceiver!!.symbol))
+                        )
+                    )
+                }
+            }
         })
     }
+
+    private fun IrClass.getValueForInstanceFieldForTheFirstTime(): IrExpression {
+        return if (context.es6mode && context is JsIrBackendContext) {
+            JsIrBuilder.buildNull(thisReceiver!!.type)
+        } else {
+            JsIrBuilder.buildGetValue(thisReceiver!!.symbol)
+        }
+    }
+
+    private fun generateInitInstanceField(instanceField: IrField, value: IrExpression): IrStatement {
+        return JsIrBuilder.buildSetField(instanceField.symbol, null, value, context.irBuiltIns.unitType)
+    }
 }
 
 private fun JsCommonBackendContext.getOrCreateGetInstanceFunction(obj: IrClass) =

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/PrimaryConstructorLowering.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.ir.backend.js.lower
 
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
 import org.jetbrains.kotlin.backend.common.DeclarationTransformer
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.backend.js.JsCommonBackendContext
@@ -17,18 +18,20 @@ import org.jetbrains.kotlin.ir.expressions.IrInstanceInitializerCall
 import org.jetbrains.kotlin.ir.expressions.impl.IrDelegatingConstructorCallImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrInstanceInitializerCallImpl
 import org.jetbrains.kotlin.ir.util.constructors
-import org.jetbrains.kotlin.ir.util.isInterface
 import org.jetbrains.kotlin.ir.util.parentAsClass
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 
+val IrDeclaration.isSyntheticPrimaryConstructor: Boolean
+    get() = origin == PrimaryConstructorLowering.SYNTHETIC_PRIMARY_CONSTRUCTOR
+
 // Create primary constructor if it doesn't exist
 class PrimaryConstructorLowering(val context: JsCommonBackendContext) : DeclarationTransformer {
 
     private var IrClass.syntheticPrimaryConstructor by context.mapping.classToSyntheticPrimaryConstructor
 
     override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
-        if (declaration is IrClass && !declaration.isInterface) {
+        if (declaration is IrClass && declaration.kind != ClassKind.INTERFACE) {
             val constructors = declaration.constructors
 
             if (constructors.any { it.isPrimary }) return null

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/SecondaryCtorLowering.kt

@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.ir.backend.js.lower
 
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
 import org.jetbrains.kotlin.backend.common.DeclarationTransformer
-import org.jetbrains.kotlin.backend.common.compilationException
 import org.jetbrains.kotlin.backend.common.getOrPut
 import org.jetbrains.kotlin.backend.common.ir.ValueRemapper
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
@@ -33,6 +32,7 @@ import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
 class SecondaryConstructorLowering(val context: JsIrBackendContext) : DeclarationTransformer {
 
@@ -234,6 +234,7 @@ private fun JsIrBackendContext.buildConstructorFactory(constructor: IrConstructo
 class SecondaryFactoryInjectorLowering(val context: JsIrBackendContext) : BodyLoweringPass {
 
     override fun lower(irBody: IrBody, container: IrDeclaration) {
+        if (context.es6mode) return
         // TODO Simplify? Is this needed at all?
         var parentFunction: IrFunction? = container as? IrFunction
         var declaration = container
@@ -266,14 +267,7 @@ private class CallsiteRedirectionTransformer(private val context: JsIrBackendCon
 
         val target = expression.symbol.owner
         return if (target.isSecondaryConstructorCall) {
-            val factory = with(context) {
-                if (es6mode) mapping.secondaryConstructorToDelegate[target]
-                    ?: compilationException(
-                        "Not found IrFunction for secondary ctor",
-                        expression
-                    )
-                else buildConstructorFactory(target, target.parentAsClass)
-            }
+            val factory = context.buildConstructorFactory(target, target.parentAsClass)
             replaceSecondaryConstructorWithFactoryFunction(expression, factory.symbol)
         } else expression
     }
@@ -285,18 +279,8 @@ private class CallsiteRedirectionTransformer(private val context: JsIrBackendCon
 
         return if (target.isSecondaryConstructorCall) {
             val klass = target.parentAsClass
-            val delegate = with(context) {
-                if (es6mode) mapping.secondaryConstructorToDelegate[target]
-                    ?: compilationException(
-                        "Not found IrFunction for secondary ctor",
-                        expression
-                    )
-                else buildConstructorDelegate(target, klass)
-            }
+            val delegate = context.buildConstructorDelegate(target, klass)
             val newCall = replaceSecondaryConstructorWithFactoryFunction(expression, delegate.symbol)
-            if (context.es6mode) {
-                return newCall
-            }
 
             val readThis = expression.run {
                 if (data is IrConstructor) {
@@ -315,16 +299,19 @@ private class CallsiteRedirectionTransformer(private val context: JsIrBackendCon
     private fun replaceSecondaryConstructorWithFactoryFunction(
         call: IrFunctionAccessExpression,
         newTarget: IrSimpleFunctionSymbol
-    ) = IrCallImpl(
-        call.startOffset, call.endOffset, call.type, newTarget,
-        typeArgumentsCount = call.typeArgumentsCount,
-        valueArgumentsCount = newTarget.owner.valueParameters.size
-    ).apply {
+    ): IrCall {
+        val irClass = call.symbol.owner.parentAsClass
+        return IrCallImpl(
+            call.startOffset, call.endOffset, call.type, newTarget,
+            typeArgumentsCount = call.typeArgumentsCount,
+            valueArgumentsCount = newTarget.owner.valueParameters.size,
+            superQualifierSymbol = irClass.symbol.takeIf { context.es6mode && call.isSyntheticDelegatingReplacement }
+        ).apply {
+            copyTypeArgumentsFrom(call)
 
-        copyTypeArgumentsFrom(call)
-
-        for (i in 0 until call.valueArgumentsCount) {
-            putValueArgument(i, call.getValueArgument(i))
+            for (i in 0 until call.valueArgumentsCount) {
+                putValueArgument(i, call.getValueArgument(i))
+            }
         }
     }
 }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/ThrowableLowering.kt

@@ -6,8 +6,8 @@
 package org.jetbrains.kotlin.ir.backend.js.lower
 
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
-import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
 import org.jetbrains.kotlin.ir.backend.js.utils.getVoid
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
@@ -21,12 +21,7 @@ import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
 
 
-class ThrowableLowering(
-    val context: JsIrBackendContext,
-    val extendThrowableFunction: IrSimpleFunctionSymbol
-) : BodyLoweringPass {
-    private val nothingNType = context.irBuiltIns.nothingNType
-
+class ThrowableLowering(val context: JsIrBackendContext, val extendThrowableFunction: IrSimpleFunctionSymbol) : BodyLoweringPass {
     private val throwableConstructors = context.throwableConstructors
     private val newThrowableFunction = context.newThrowableSymbol
 
@@ -64,6 +59,8 @@ class ThrowableLowering(
         }
 
     inner class Transformer : IrElementTransformer<IrDeclarationParent> {
+        private val anyConstructor = context.irBuiltIns.anyClass.constructors.first()
+
         override fun visitClass(declaration: IrClass, data: IrDeclarationParent) = super.visitClass(declaration, declaration)
 
         override fun visitConstructorCall(expression: IrConstructorCall, data: IrDeclarationParent): IrExpression {
@@ -93,7 +90,7 @@ class ThrowableLowering(
             val klass = data as IrClass
             val thisReceiver = IrGetValueImpl(expression.startOffset, expression.endOffset, klass.thisReceiver!!.symbol)
 
-            return expression.run {
+            val expressionReplacement = expression.run {
                 IrCallImpl(
                     startOffset, endOffset, type, extendThrowableFunction,
                     valueArgumentsCount = 3,
@@ -104,6 +101,25 @@ class ThrowableLowering(
                     it.putValueArgument(2, causeArg)
                 }
             }
+
+            return if (!context.es6mode) {
+                expressionReplacement
+            } else {
+                JsIrBuilder.buildComposite(
+                    context.irBuiltIns.unitType,
+                    listOf(
+                        IrDelegatingConstructorCallImpl(
+                            expression.startOffset,
+                            expression.endOffset,
+                            context.irBuiltIns.anyType,
+                            anyConstructor,
+                            0,
+                            0
+                        ),
+                        expressionReplacement
+                    )
+                )
+            }
         }
     }
 }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/optimizations.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2010-2022 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.ir.backend.js
+
+import org.jetbrains.kotlin.backend.common.phaser.PhaseConfig
+import org.jetbrains.kotlin.backend.common.phaser.invokeToplevel
+import org.jetbrains.kotlin.ir.backend.js.dce.eliminateDeadDeclarations
+import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
+
+fun optimizeProgramByIr(
+    modules: Iterable<IrModuleFragment>,
+    context: JsIrBackendContext,
+    removeUnusedAssociatedObjects: Boolean
+) {
+    eliminateDeadDeclarations(modules, context, removeUnusedAssociatedObjects)
+    jsOptimizationPhases.invokeToplevel(PhaseConfig(jsOptimizationPhases), context, modules)
+}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrElementToJsExpressionTransformer.kt

@@ -166,7 +166,7 @@ class IrElementToJsExpressionTransformer : BaseIrElementToJsNodeTransformer<JsEx
         }
 
         return if (context.staticContext.backendContext.es6mode) {
-            JsInvocation(JsNameRef("super"), arguments)
+            JsInvocation(JsSuperRef(), arguments)
         } else {
             JsInvocation(callFuncRef, listOf(thisRef) + arguments)
         }.withSource(expression, context)

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrElementToJsStatementTransformer.kt

@@ -65,7 +65,11 @@ class IrElementToJsStatementTransformer : BaseIrElementToJsNodeTransformer<JsSta
     }
 
     override fun visitComposite(expression: IrComposite, context: JsGenerationContext): JsStatement {
-        return JsBlock(expression.statements.map { it.accept(this, context) }).withSource(expression, context)
+        return if (expression.statements.isEmpty()) {
+            JsEmpty
+        } else {
+            JsBlock(expression.statements.map { it.accept(this, context) }).withSource(expression, context)
+        }
     }
 
     override fun visitExpression(expression: IrExpression, context: JsGenerationContext): JsStatement {

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrModuleToJsTransformer.kt

@@ -8,7 +8,6 @@ package org.jetbrains.kotlin.ir.backend.js.transformers.irToJs
 import org.jetbrains.kotlin.backend.common.serialization.checkIsFunctionInterface
 import org.jetbrains.kotlin.config.CommonConfigurationKeys
 import org.jetbrains.kotlin.ir.backend.js.*
-import org.jetbrains.kotlin.ir.backend.js.dce.eliminateDeadDeclarations
 import org.jetbrains.kotlin.ir.backend.js.export.*
 import org.jetbrains.kotlin.ir.backend.js.lower.StaticMembersLowering
 import org.jetbrains.kotlin.ir.backend.js.lower.isBuiltInClass
@@ -46,29 +45,33 @@ val IrModuleFragment.safeName: String
     get() = name.asString().safeModuleName
 
 enum class TranslationMode(
-    val dce: Boolean,
+    val production: Boolean,
     val perModule: Boolean,
     val minimizedMemberNames: Boolean,
 ) {
-    FULL(dce = false, perModule = false, minimizedMemberNames = false),
-    FULL_DCE(dce = true, perModule = false, minimizedMemberNames = false),
-    FULL_DCE_MINIMIZED_NAMES(dce = true, perModule = false, minimizedMemberNames = true),
-    PER_MODULE(dce = false, perModule = true, minimizedMemberNames = false),
-    PER_MODULE_DCE(dce = true, perModule = true, minimizedMemberNames = false),
-    PER_MODULE_DCE_MINIMIZED_NAMES(dce = true, perModule = true, minimizedMemberNames = true);
+    FULL_DEV(production = false, perModule = false, minimizedMemberNames = false),
+    FULL_PROD(production = true, perModule = false, minimizedMemberNames = false),
+    FULL_PROD_MINIMIZED_NAMES(production = true, perModule = false, minimizedMemberNames = true),
+    PER_MODULE_DEV(production = false, perModule = true, minimizedMemberNames = false),
+    PER_MODULE_PROD(production = true, perModule = true, minimizedMemberNames = false),
+    PER_MODULE_PROD_MINIMIZED_NAMES(production = true, perModule = true, minimizedMemberNames = true);
 
     companion object {
-        fun fromFlags(dce: Boolean, perModule: Boolean, minimizedMemberNames: Boolean): TranslationMode {
+        fun fromFlags(
+            production: Boolean,
+            perModule: Boolean,
+            minimizedMemberNames: Boolean
+        ): TranslationMode {
             return if (perModule) {
-                if (dce) {
-                    if (minimizedMemberNames) PER_MODULE_DCE_MINIMIZED_NAMES
-                    else PER_MODULE_DCE
-                } else PER_MODULE
+                if (production) {
+                    if (minimizedMemberNames) PER_MODULE_PROD_MINIMIZED_NAMES
+                    else PER_MODULE_PROD
+                } else PER_MODULE_DEV
             } else {
-                if (dce) {
-                    if (minimizedMemberNames) FULL_DCE_MINIMIZED_NAMES
-                    else FULL_DCE
-                } else FULL
+                if (production) {
+                    if (minimizedMemberNames) FULL_PROD_MINIMIZED_NAMES
+                    else FULL_PROD
+                } else FULL_DEV
             }
         }
     }
@@ -146,15 +149,15 @@ class IrModuleToJsTransformer(
 
         val result = EnumMap<TranslationMode, CompilationOutputs>(TranslationMode::class.java)
 
-        modes.filter { !it.dce }.forEach {
+        modes.filter { !it.production }.forEach {
             result[it] = makeJsCodeGeneratorFromIr(exportData, it).generateJsCode(relativeRequirePath, true)
         }
 
-        if (modes.any { it.dce }) {
-            eliminateDeadDeclarations(modules, backendContext, removeUnusedAssociatedObjects)
+        if (modes.any { it.production }) {
+            optimizeProgramByIr(modules, backendContext, removeUnusedAssociatedObjects)
         }
 
-        modes.filter { it.dce }.forEach {
+        modes.filter { it.production }.forEach {
             result[it] = makeJsCodeGeneratorFromIr(exportData, it).generateJsCode(relativeRequirePath, true)
         }
 
@@ -165,8 +168,8 @@ class IrModuleToJsTransformer(
         val exportData = associateIrAndExport(modules)
         doStaticMembersLowering(modules)
 
-        if (mode.dce) {
-            eliminateDeadDeclarations(modules, backendContext, removeUnusedAssociatedObjects)
+        if (mode.production) {
+            optimizeProgramByIr(modules, backendContext, removeUnusedAssociatedObjects)
         }
 
         return makeJsCodeGeneratorFromIr(exportData, mode)
@@ -242,8 +245,12 @@ class IrModuleToJsTransformer(
 
         val internalModuleName = ReservedJsNames.makeInternalModuleName().takeIf { !isEsModules }
         val globalNames = NameTable<String>(globalNameScope)
+
+        val statements = result.declarations.statements
+        val fileStatements = fileExports.file.accept(IrFileToJsTransformer(useBareParameterNames = true), staticContext).statements
+
         val exportStatements =
-            ExportModelToJsStatements(staticContext, { globalNames.declareFreshName(it, it) }).generateModuleExport(
+            ExportModelToJsStatements(staticContext, backendContext.es6mode, { globalNames.declareFreshName(it, it) }).generateModuleExport(
                 ExportedModule(mainModuleName, moduleKind, fileExports.exports),
                 internalModuleName,
                 isEsModules
@@ -252,9 +259,6 @@ class IrModuleToJsTransformer(
         result.exports.statements += exportStatements
         result.dts = fileExports.tsDeclarations
 
-        val statements = result.declarations.statements
-
-        val fileStatements = fileExports.file.accept(IrFileToJsTransformer(useBareParameterNames = true), staticContext).statements
         if (fileStatements.isNotEmpty()) {
             var startComment = ""
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt

@@ -6,39 +6,32 @@
 package org.jetbrains.kotlin.ir.backend.js.transformers.irToJs
 
 import org.jetbrains.kotlin.backend.common.compilationException
-import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
 import org.jetbrains.kotlin.descriptors.Modality
-import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.export.isAllowedFakeOverriddenDeclaration
 import org.jetbrains.kotlin.ir.backend.js.export.isExported
 import org.jetbrains.kotlin.ir.backend.js.export.isOverriddenExported
+import org.jetbrains.kotlin.ir.backend.js.lower.isEs6ConstructorReplacement
 import org.jetbrains.kotlin.ir.backend.js.utils.*
-import org.jetbrains.kotlin.ir.builders.irCall
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.expressions.IrClassReference
-import org.jetbrains.kotlin.ir.expressions.IrExpression
-import org.jetbrains.kotlin.ir.expressions.impl.IrVarargImpl
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.symbols.IrClassifierSymbol
-import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.js.backend.ast.*
 import org.jetbrains.kotlin.js.common.isValidES5Identifier
 import org.jetbrains.kotlin.utils.addIfNotNull
-import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
 class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationContext) {
     private val className = context.getNameForClass(irClass)
     private val classNameRef = className.makeRef()
     private val baseClass: IrType? = irClass.superTypes.firstOrNull { !it.classifierOrFail.isInterface }
 
+    private val classPrototypeRef by lazy { prototypeOf(classNameRef, context.staticContext) }
     private val baseClassRef by lazy { // Lazy in case was not collected by namer during JsClassGenerator construction
         if (baseClass != null && !baseClass.isAny()) baseClass.getClassRef(context) else null
     }
-    private val classPrototypeRef = prototypeOf(classNameRef, context.staticContext)
     private val classBlock = JsCompositeBlock()
     private val classModel = JsIrClassModel(irClass)
 
@@ -67,14 +60,9 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
             when (declaration) {
                 is IrConstructor -> {
                     if (es6mode) {
-                        declaration.accept(IrFunctionToJsTransformer(), context).let {
-                            //HACK: add superCall to Error
-                            if ((baseClass?.classifierOrNull?.owner as? IrClass)?.symbol === context.staticContext.backendContext.throwableClass) {
-                                it.body.statements.add(0, JsInvocation(JsNameRef("super")).makeStmt())
-                            }
-
-                            if (it.body.statements.any { it !is JsEmpty }) {
-                                jsClass.constructor = it
+                        declaration.accept(IrFunctionToJsTransformer(), context).let { fn ->
+                            if (fn.body.statements.any { it !is JsEmpty && !it.isSimpleSuperCall(fn) }) {
+                                jsClass.constructor = fn
                             }
                         }
                     } else {
@@ -85,13 +73,15 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
                     properties.addIfNotNull(declaration.correspondingPropertySymbol?.owner)
 
                     if (es6mode) {
-                        val (memberRef, function) = generateMemberFunction(declaration)
-                        function?.let { jsClass.members += it }
-                        declaration.generateAssignmentIfMangled(memberRef)
+                        if (declaration.isEs6ConstructorReplacement && irClass.isInterface) continue
+                        val (memberName, function) = generateMemberFunction(declaration)
+                        function?.let { jsClass.members += it.escapedIfNeed() }
+                        declaration.generateAssignmentIfMangled(memberName)
                     } else {
-                        val (memberRef, function) = generateMemberFunction(declaration)
+                        val (memberName, function) = generateMemberFunction(declaration)
+                        val memberRef = jsElementAccess(memberName, classPrototypeRef)
                         function?.let { classBlock.statements += jsAssignment(memberRef, it.apply { name = null }).makeStmt() }
-                        declaration.generateAssignmentIfMangled(memberRef)
+                        declaration.generateAssignmentIfMangled(memberName)
                     }
                 }
                 is IrClass -> {
@@ -164,6 +154,7 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
                     getterOverridesExternal ||
                     property.getJsName() != null
                 ) {
+                    val propertyName = context.getNameForProperty(property)
 
                     // Use "direct dispatch" for final properties, i. e. instead of this:
                     //     Object.defineProperty(Foo.prototype, 'prop', {
@@ -180,7 +171,7 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
 
                     val getterForwarder = property.getter
                         .takeIf { it.shouldExportAccessor(context.staticContext.backendContext) }
-                        .getOrGenerateIfFinal {
+                        .getOrGenerateIfFinalOrEs6Mode {
                             propertyAccessorForwarder("getter forwarder") {
                                 JsReturn(JsInvocation(it))
                             }
@@ -188,7 +179,7 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
 
                     val setterForwarder = property.setter
                         .takeIf { it.shouldExportAccessor(context.staticContext.backendContext) }
-                        .getOrGenerateIfFinal {
+                        .getOrGenerateIfFinalOrEs6Mode {
                             val setterArgName = JsName("value", false)
                             propertyAccessorForwarder("setter forwarder") {
                                 JsInvocation(it, JsNameRef(setterArgName)).makeStmt()
@@ -197,29 +188,37 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
                             }
                         }
 
-                    classBlock.statements += JsExpressionStatement(
-                        defineProperty(
-                            classPrototypeRef,
-                            context.getNameForProperty(property).ident,
-                            getter = getterForwarder,
-                            setter = setterForwarder,
-                            context.staticContext
+                    if (es6mode) {
+                        jsClass.members += listOfNotNull(
+                            (getterForwarder as? JsFunction)?.apply {
+                                name = propertyName
+                                modifiers.add(JsFunction.Modifier.GET)
+                            },
+                            (setterForwarder as? JsFunction)?.apply {
+                                name = propertyName
+                                modifiers.add(JsFunction.Modifier.SET)
+                            }
                         )
-                    )
+                    } else {
+                        classBlock.statements += JsExpressionStatement(
+                            defineProperty(classPrototypeRef, propertyName.ident, getterForwarder, setterForwarder, context.staticContext)
+                        )
+                    }
                 }
             }
         }
 
-        classModel.preDeclarationBlock.statements += generateSetMetadataCall()
+        val metadataPlace = if (es6mode) classModel.postDeclarationBlock else classModel.preDeclarationBlock
 
+        metadataPlace.statements += generateSetMetadataCall()
         context.staticContext.classModels[irClass.symbol] = classModel
 
         return classBlock
     }
 
-    private inline fun IrSimpleFunction?.getOrGenerateIfFinal(generateFunc: IrSimpleFunction.() -> JsFunction?): JsExpression? {
+    private inline fun IrSimpleFunction?.getOrGenerateIfFinalOrEs6Mode(generateFunc: IrSimpleFunction.() -> JsFunction?): JsExpression? {
         if (this == null) return null
-        return if (modality == Modality.FINAL) accessorRef() else generateFunc()
+        return if (!es6mode && modality == Modality.FINAL) accessorRef() else generateFunc()
     }
 
     private fun IrSimpleFunction.isDefinedInsideExportedInterface(): Boolean {
@@ -237,13 +236,13 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
             )
         }
 
-    private fun IrSimpleFunction.generateAssignmentIfMangled(memberRef: JsExpression) {
+    private fun IrSimpleFunction.generateAssignmentIfMangled(memberName: JsName) {
         if (
             irClass.isExported(context.staticContext.backendContext) &&
             visibility.isPublicAPI && hasMangledName() &&
             correspondingPropertySymbol == null
         ) {
-            classBlock.statements += jsAssignment(prototypeAccessRef(), memberRef).makeStmt()
+            classBlock.statements += jsAssignment(prototypeAccessRef(), jsElementAccess(memberName, classPrototypeRef)).makeStmt()
         }
     }
 
@@ -259,9 +258,8 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
         return isInterface && !isEffectivelyExternal()
     }
 
-    private fun generateMemberFunction(declaration: IrSimpleFunction): Pair<JsExpression, JsFunction?> {
+    private fun generateMemberFunction(declaration: IrSimpleFunction): Pair<JsName, JsFunction?> {
         val memberName = context.getNameForMemberFunction(declaration.realOverrideTarget)
-        val memberRef = jsElementAccess(memberName.ident, classPrototypeRef)
 
         if (declaration.isReal && declaration.body != null) {
             val translatedFunction: JsFunction = declaration.accept(IrFunctionToJsTransformer(), context)
@@ -269,10 +267,10 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
 
             if (irClass.isInterface) {
                 classModel.preDeclarationBlock.statements += translatedFunction.makeStmt()
-                return Pair(memberRef, null)
+                return Pair(memberName, null)
             }
 
-            return Pair(memberRef, translatedFunction)
+            return Pair(memberName, translatedFunction)
         }
 
         // do not generate code like
@@ -294,7 +292,10 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
 
                     if (implClassDeclaration.shouldCopyFrom()) {
                         val reference = context.getNameForStaticDeclaration(it).makeRef()
-                        classModel.postDeclarationBlock.statements += jsAssignment(memberRef, reference).makeStmt()
+                        classModel.postDeclarationBlock.statements += jsAssignment(
+                            jsElementAccess(memberName, classPrototypeRef),
+                            reference
+                        ).makeStmt()
                         if (isFakeOverride) {
                             classModel.postDeclarationBlock.statements += missedOverrides
                                 .map { missedOverride ->
@@ -307,7 +308,7 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
                 }
         }
 
-        return Pair(memberRef, null)
+        return Pair(memberName, null)
     }
 
     private fun maybeGeneratePrimaryConstructor() {
@@ -322,7 +323,7 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
         val setMetadataFor = context.staticContext.backendContext.intrinsics.setMetadataForSymbol.owner
 
         val ctor = classNameRef
-        val parent = baseClassRef
+        val parent = baseClassRef?.takeIf { !es6mode }
         val name = generateSimpleName()
         val interfaces = generateInterfacesList()
         val metadataConstructor = getMetadataConstructor()
@@ -352,8 +353,6 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
 
     private fun IrType.isFunctionType() = isFunctionOrKFunction() || isSuspendFunctionOrKFunction()
 
-    private fun isCoroutineClass(): Boolean = irClass.superTypes.any { it.isSuspendFunctionTypeOrSubtype() }
-
     private fun generateSimpleName(): JsStringLiteral? {
         return irClass.name.takeIf { !it.isSpecial }?.let { JsStringLiteral(it.identifier) }
     }
@@ -386,7 +385,7 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
             .distinct()
             .map { JsIntLiteral(it) }
 
-        return JsArrayLiteral(arity)
+        return JsArrayLiteral(arity).takeIf { arity.isNotEmpty() }
     }
 
     private fun generateAssociatedObjectKey(): JsIntLiteral? {
@@ -411,6 +410,31 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
     }
 }
 
+fun JsFunction.escapedIfNeed(): JsFunction {
+    if (name?.ident?.isValidES5Identifier() == false) {
+        name = JsName("'${name.ident}'", name.isTemporary)
+    }
+    return this
+
+}
+
+fun JsStatement.isSimpleSuperCall(container: JsFunction): Boolean {
+    if (this !is JsExpressionStatement) return false
+    val invocation = expression as? JsInvocation ?: return false
+    if (invocation.qualifier !is JsSuperRef || container.parameters.size != invocation.arguments.size) return false
+
+    for (i in 0..container.parameters.lastIndex) {
+        val declaredParameter = container.parameters[i]
+        val providedParameter = (invocation.arguments[i] as? JsNameRef)?.takeIf { it.qualifier == null } ?: return false
+
+        if (declaredParameter.name != providedParameter.name) {
+            return false
+        }
+    }
+
+    return true
+}
+
 fun IrSimpleFunction?.shouldExportAccessor(context: JsIrBackendContext): Boolean {
     if (this == null) return false
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsIntrinsicTransformers.kt

@@ -119,11 +119,6 @@ class JsIntrinsicTransformers(backendContext: JsIrBackendContext) {
                 JsObjectLiteral()
             }
 
-            add(intrinsics.es6DefaultType) { call, context ->
-                val typeArgument = call.getTypeArgument(0)!!
-                typeArgument.getClassRef(context)
-            }
-
             addIfNotNull(intrinsics.jsCode) { call, _ ->
                 compilationException(
                     "Should not be called",
@@ -272,6 +267,16 @@ class JsIntrinsicTransformers(backendContext: JsIrBackendContext) {
             add(intrinsics.jsInvokeSuspendSuperTypeWithReceiverAndParam, suspendInvokeTransform)
 
             add(intrinsics.jsArguments) { _, _ -> Namer.ARGUMENTS }
+
+            add(intrinsics.jsNewAnonymousClass) { call, context ->
+                val baseClass = translateCallArguments(call, context).single() as JsNameRef
+                JsClass(baseClass = baseClass)
+            }
+
+            add(intrinsics.void.owner.getter!!.symbol) { _, context ->
+                val backingField = context.getNameForField(intrinsics.void.owner.backingField!!)
+                JsNameRef(backingField)
+            }
         }
     }
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/Merger.kt

@@ -39,8 +39,9 @@ class Merger(
                     importStatements.putIfAbsent(declaration, JsVars(JsVars.JsVar(importName, rename(importExpression))))
                 }
 
-                val classModels = mutableMapOf<JsName, JsIrIcClassModel>() + f.classes
-                f.classes.clear()
+                val classModels = (mutableMapOf<JsName, JsIrIcClassModel>() + f.classes)
+                    .also { f.classes.clear() }
+
                 classModels.entries.forEach { (name, model) ->
                     f.classes[rename(name)] = JsIrIcClassModel(model.superClasses.map { rename(it) }).also {
                         it.preDeclarationBlock.statements += model.preDeclarationBlock.statements

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/jsAstUtils.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.backend.js.JsLoweredDeclarationOrigin
 import org.jetbrains.kotlin.ir.backend.js.JsStatementOrigins
+import org.jetbrains.kotlin.ir.backend.js.lower.*
 import org.jetbrains.kotlin.ir.backend.js.sourceMapsInfo
 import org.jetbrains.kotlin.ir.backend.js.utils.*
 import org.jetbrains.kotlin.ir.declarations.*
@@ -32,7 +33,6 @@ import java.io.IOException
 import java.io.InputStreamReader
 import java.nio.charset.StandardCharsets
 
-
 fun jsUndefined(context: IrNamer, backendContext: JsIrBackendContext): JsExpression {
     return when (val void = backendContext.getVoid()) {
         is IrGetField -> context.getNameForField(void.symbol.owner).makeRef()
@@ -114,6 +114,7 @@ fun translateFunction(declaration: IrFunction, name: JsName?, context: JsGenerat
     val body = declaration.body?.accept(IrElementToJsStatementTransformer(), functionContext) as? JsBlock ?: JsBlock()
 
     val function = JsFunction(emptyScope, body, "member function ${name ?: "annon"}")
+        .apply { if (declaration.isEs6ConstructorReplacement) modifiers.add(JsFunction.Modifier.STATIC) }
         .withSource(declaration, context, useNameOf = declaration)
 
     function.name = name
@@ -147,6 +148,7 @@ fun translateCall(
     transformer: IrElementToJsExpressionTransformer
 ): JsExpression {
     val function = expression.symbol.owner.realOverrideTarget
+    val currentDispatchReceiver = context.currentFunction?.parentClassOrNull
 
     context.staticContext.intrinsics[function.symbol]?.let {
         return it(expression, context)
@@ -194,6 +196,10 @@ fun translateCall(
             Pair(function, superQualifier.owner)
         }
 
+        if (expression.isSyntheticDelegatingReplacement || currentDispatchReceiver.canUseSuperRef(function, context, klass)) {
+            return JsInvocation(JsNameRef(context.getNameForMemberFunction(target), JsSuperRef()), arguments)
+        }
+
         val callRef = if (klass.isInterface) {
             val nameForStaticDeclaration = context.getNameForStaticDeclaration(target)
             JsNameRef(Namer.CALL_FUNCTION, JsNameRef(nameForStaticDeclaration))
@@ -373,12 +379,15 @@ fun translateCallArguments(
 ): List<JsExpression> {
     val size = expression.valueArgumentsCount
 
-    val varargParameterIndex = expression.symbol.owner.realOverrideTarget.varargParameterIndex()
+    val function = expression.symbol.owner
+    val varargParameterIndex = function.realOverrideTarget.varargParameterIndex()
 
     val validWithNullArgs = expression.validWithNullArgs()
     val arguments = (0 until size)
         .mapTo(ArrayList(size)) { index ->
-            expression.getValueArgument(index).checkOnNullability(validWithNullArgs)
+            expression.getValueArgument(index).checkOnNullability(
+                validWithNullArgs || function.valueParameters[index].isBoxParameter
+            )
         }
         .dropLastWhile {
             allowDropTailVoids &&
@@ -635,3 +644,11 @@ private val nameMappingOriginAllowList = setOf(
     BOUND_VALUE_PARAMETER,
     JsLoweredDeclarationOrigin.JS_SHADOWED_DEFAULT_PARAMETER,
 )
+
+private fun IrClass?.canUseSuperRef(function: IrFunction, context: JsGenerationContext, superClass: IrClass): Boolean {
+    return this != null &&
+            function.origin != IrDeclarationOrigin.LOWERED_SUSPEND_FUNCTION &&
+            context.staticContext.backendContext.es6mode &&
+            !superClass.isInterface && !isInner && !isLocal &&
+            context.currentFunction?.isEs6ConstructorReplacement != true
+}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/resolveTemporaryNames.kt

@@ -74,8 +74,20 @@ private fun JsNode.computeScopes(): Scope {
     accept(object : RecursiveJsVisitor() {
         var currentScope: Scope = rootScope
 
-        override fun visitFunction(x: JsFunction) {
+        override fun visitClass(x: JsClass) {
             x.name?.let { currentScope.declaredNames += it }
+            // We need it to not rename methods and fields inside class body
+            // Because if they are in clash with something, it means overriding
+            x.constructor?.accept(this)
+            x.members.forEach { visitFunction(it, shouldReserveName = false) }
+        }
+
+        override fun visitFunction(x: JsFunction) {
+            visitFunction(x, shouldReserveName = true)
+        }
+
+        fun visitFunction(x: JsFunction, shouldReserveName: Boolean) {
+            x.name?.takeIf { shouldReserveName }?.let { currentScope.declaredNames += it }
             val oldScope = currentScope
             currentScope = Scope().apply {
                 currentScope.children += this

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/AnnotationUtils.kt

@@ -12,7 +12,6 @@ import org.jetbrains.kotlin.ir.declarations.IrOverridableDeclaration
 import org.jetbrains.kotlin.ir.expressions.IrClassReference
 import org.jetbrains.kotlin.ir.expressions.IrConst
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
-import org.jetbrains.kotlin.ir.expressions.IrVararg
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.name.FqName
@@ -37,10 +36,6 @@ object JsAnnotations {
 fun IrConstructorCall.getSingleConstStringArgument() =
     (getValueArgument(0) as IrConst<String>).value
 
-@Suppress("UNCHECKED_CAST")
-fun IrConstructorCall.getClassReferencVarargArguments() =
-    (getValueArgument(0) as? IrVararg)?.elements as? List<IrClassReference>
-
 fun IrAnnotationContainer.getJsModule(): String? =
     getAnnotation(JsAnnotations.jsModuleFqn)?.getSingleConstStringArgument()
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/IrJsUtils.kt

@@ -9,16 +9,28 @@ import org.jetbrains.kotlin.descriptors.isClass
 import org.jetbrains.kotlin.descriptors.isInterface
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.backend.js.JsStatementOrigins
 import org.jetbrains.kotlin.ir.backend.js.export.isExported
+import org.jetbrains.kotlin.ir.backend.js.ir.JsIrBuilder
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.IrFunctionAccessExpression
 import org.jetbrains.kotlin.ir.expressions.IrReturn
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetFieldImpl
 import org.jetbrains.kotlin.ir.symbols.IrReturnableBlockSymbol
+import org.jetbrains.kotlin.ir.types.IrType
+import org.jetbrains.kotlin.ir.util.defaultType
+import org.jetbrains.kotlin.ir.util.isAnnotationClass
+import org.jetbrains.kotlin.ir.util.parentAsClass
 import org.jetbrains.kotlin.ir.util.parentClassOrNull
 import org.jetbrains.kotlin.name.FqName
 
+fun IrClass.jsConstructorReference(context: JsIrBackendContext): IrExpression {
+    return JsIrBuilder.buildCall(context.intrinsics.jsClass, origin = JsStatementOrigins.CLASS_REFERENCE)
+        .apply { putTypeArgument(0, defaultType) }
+}
+
 fun IrDeclaration.isExportedMember(context: JsIrBackendContext) =
     (this is IrDeclarationWithVisibility && visibility.isPublicAPI) &&
             parentClassOrNull?.isExported(context) == true
@@ -42,10 +54,23 @@ fun IrDeclarationWithName.getFqNameWithJsNameWhenAvailable(shouldIncludePackage:
     }
 }
 
+fun IrConstructor.hasStrictSignature(context: JsIrBackendContext): Boolean {
+    val primitives = with(context.irBuiltIns) { primitiveTypesToPrimitiveArrays.values + stringClass }
+    return with(parentAsClass) {
+        isExternal || isExpect || isAnnotationClass || context.inlineClassesUtils.isClassInlineLike(this) || symbol in primitives
+    }
+}
+
 private fun getKotlinOrJsQualifier(parent: IrPackageFragment, shouldIncludePackage: Boolean): FqName? {
     return (parent as? IrFile)?.getJsQualifier()?.let { FqName(it) } ?: parent.fqName.takeIf { shouldIncludePackage }
 }
 
+val IrFunctionAccessExpression.typeArguments: List<IrType?>
+    get() = List(typeArgumentsCount) { getTypeArgument(it) }
+
+val IrFunctionAccessExpression.valueArguments: List<IrExpression?>
+    get() = List(valueArgumentsCount) { getValueArgument(it) }
+
 // TODO: the code is written to pass Repl tests, so we should understand. why in Repl tests we don't have backingField
 fun JsIrBackendContext.getVoid(): IrExpression =
     intrinsics.void.owner.backingField?.let {
@@ -60,3 +85,8 @@ fun JsIrBackendContext.getVoid(): IrExpression =
         UNDEFINED_OFFSET,
         irBuiltIns.nothingNType
     )
+
+fun irEmpty(context: JsIrBackendContext): IrExpression {
+    return JsIrBuilder.buildComposite(context.dynamicType, emptyList())
+}
+

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/Namer.kt

@@ -15,10 +15,13 @@ object Namer {
 
     val OUTER_NAME = "\$outer"
     val UNREACHABLE_NAME = "\$unreachable"
+    val THROWABLE_CONSTRUCTOR = "\$throwableCtor"
 
     val DELEGATE = "\$delegate"
 
     val IMPLICIT_RECEIVER_NAME = "this"
+    val SYNTHETIC_RECEIVER_NAME = "\$this"
+    val ES6_BOX_PARAMETER_NAME = "\$box"
 
     val ARGUMENTS = JsNameRef("arguments")
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/Reference.kt

@@ -0,0 +1,10 @@
+/*
+ * Copyright 2010-2022 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.ir.backend.js.utils
+
+class MutableReference<T>(var value: T)
+
+fun <T> mutableReferenceOf(value: T): MutableReference<T> = MutableReference(value)

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/serialization/Constants.kt

@@ -54,4 +54,6 @@ object ExpressionIds {
     const val PROPERTY_REFERENCE = 19
     const val INVOCATION = 20
     const val NEW = 21
+    const val CLASS = 22
+    const val SUPER_REF = 23
 }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/serialization/JsIrAstDeserializer.kt

@@ -240,6 +240,7 @@ private class JsIrAstDeserializer(private val source: ByteArray) {
     private val sideEffectKindValues = SideEffectKind.values()
     private val jsBinaryOperatorValues = JsBinaryOperator.values()
     private val jsUnaryOperatorValues = JsUnaryOperator.values()
+    private val jsFunctionModifiersValues = JsFunction.Modifier.values()
 
     private fun readExpression(): JsExpression {
         return withComments {
@@ -249,6 +250,9 @@ private class JsIrAstDeserializer(private val source: ByteArray) {
                         THIS_REF -> {
                             JsThisRef()
                         }
+                        SUPER_REF -> {
+                            JsSuperRef()
+                        }
                         NULL -> {
                             JsNullLiteral()
                         }
@@ -283,10 +287,15 @@ private class JsIrAstDeserializer(private val source: ByteArray) {
                             )
                         }
                         FUNCTION -> {
-                            JsFunction(scope, readBlock(), "").apply {
-                                readRepeated { parameters += readParameter() }
-                                ifTrue { name = nameTable[readInt()] }
-                                isLocal = readBoolean()
+                            readFunction()
+                        }
+                        CLASS -> {
+                            JsClass(
+                                ifTrue { nameTable[readInt()] },
+                                ifTrue { nameTable[readInt()].makeRef() },
+                                ifTrue { readFunction() },
+                            ).apply {
+                                readRepeated { members += readFunction() }
                             }
                         }
                         DOC_COMMENT -> {
@@ -353,6 +362,15 @@ private class JsIrAstDeserializer(private val source: ByteArray) {
         }
     }
 
+    private fun readFunction(): JsFunction {
+        return JsFunction(scope, readBlock(), "").apply {
+            readRepeated { parameters += readParameter() }
+            readRepeated { modifiers += jsFunctionModifiersValues[readInt()] }
+            ifTrue { name = nameTable[readInt()] }
+            isLocal = readBoolean()
+        }
+    }
+
     private fun readJsImportedModule(): JsImportedModule {
         return JsImportedModule(
             stringTable[readInt()],
@@ -447,4 +465,4 @@ private class JsIrAstDeserializer(private val source: ByteArray) {
             ifTrue { this.commentsAfterNode = readArray { readComment() }.toList() }
         }
     }
-}
+}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/serialization/JsIrAstSerializer.kt

@@ -336,6 +336,10 @@ private class JsIrAstSerializer {
                 writeByte(ExpressionIds.THIS_REF)
             }
 
+            override fun visitSuper(x: JsSuperRef) {
+                writeByte(ExpressionIds.SUPER_REF)
+            }
+
             override fun visitNull(x: JsNullLiteral) {
                 writeByte(ExpressionIds.NULL)
             }
@@ -387,12 +391,24 @@ private class JsIrAstSerializer {
 
             override fun visitFunction(x: JsFunction) {
                 writeByte(ExpressionIds.FUNCTION)
-                writeBlock(x.body)
-                writeCollection(x.parameters) { writeParameter(it) }
+                writeFunction(x)
+            }
+
+            override fun visitClass(x: JsClass) {
+                writeByte(ExpressionIds.CLASS)
                 ifNotNull(x.name) {
                     writeInt(internalizeName(it))
                 }
-                writeBoolean(x.isLocal)
+                // TODO: add more complex JsNameRef parsing in future when we will support `class` expressions inside a `js` call
+                ifNotNull(x.baseClass?.name) {
+                    writeInt(internalizeName(it))
+                }
+                ifNotNull(x.constructor) {
+                    writeFunction(it)
+                }
+                writeCollection(x.members) {
+                    writeFunction(it)
+                }
             }
 
             override fun visitDocComment(comment: JsDocComment) {
@@ -494,6 +510,16 @@ private class JsIrAstSerializer {
         ifNotNull(module.plainReference) { writeExpression(it) }
     }
 
+    private fun DataWriter.writeFunction(function: JsFunction) {
+        writeBlock(function.body)
+        writeCollection(function.parameters) { writeParameter(it) }
+        writeCollection(function.modifiers) { writeInt(it.ordinal) }
+        ifNotNull(function.name) {
+            writeInt(internalizeName(it))
+        }
+        writeBoolean(function.isLocal)
+    }
+
     private fun DataWriter.writeParameter(parameter: JsParameter) {
         writeInt(internalizeName(parameter.name))
         writeBoolean(parameter.hasDefaultValue)

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrStatementOrigin.kt

@@ -5,8 +5,6 @@
 
 package org.jetbrains.kotlin.ir.expressions
 
-import org.jetbrains.kotlin.ir.declarations.IrDeclarationOriginImpl
-
 abstract class IrStatementOriginImpl(val debugName: String) : IrStatementOrigin {
     override fun toString(): String = debugName
 }

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IrUtils.kt

@@ -205,6 +205,12 @@ val IrProperty.isSimpleProperty: Boolean
 val IrClass.functions: Sequence<IrSimpleFunction>
     get() = declarations.asSequence().filterIsInstance<IrSimpleFunction>()
 
+val IrClass.superClass: IrClass?
+    get() = superTypes
+        .firstOrNull { !it.isInterface() && !it.isAny() }
+        ?.classOrNull
+        ?.owner
+
 val IrClassSymbol.functions: Sequence<IrSimpleFunctionSymbol>
     get() = owner.functions.map { it.symbol }
 
@@ -823,8 +829,11 @@ fun IrFunction.copyValueParametersFrom(from: IrFunction, substitutionMap: Map<Ir
 fun IrFunction.copyParameterDeclarationsFrom(from: IrFunction) {
     assert(typeParameters.isEmpty())
     copyTypeParametersFrom(from)
-    val substitutionMap = makeTypeParameterSubstitutionMap(from, this)
-    copyValueParametersFrom(from, substitutionMap)
+    copyValueParametersFrom(from)
+}
+
+fun IrFunction.copyValueParametersFrom(from: IrFunction) {
+    copyValueParametersFrom(from, makeTypeParameterSubstitutionMap(from, this))
 }
 
 fun IrTypeParametersContainer.copyTypeParameters(

compiler/testData/cli/js/jsExtraHelp.out

@@ -45,6 +45,7 @@ where advanced options include:
   -Xtyped-arrays             Translate primitive arrays to JS typed arrays
   -Xuse-deprecated-legacy-compiler
                              Use deprecated legacy compiler without error
+  -Xes-classes               Generated JavaScript will use ES2015 classes.
   -Xwasm                     Use experimental WebAssembly compiler backend
   -Xwasm-debug-info          Add debug info to WebAssembly compiled module
   -Xwasm-enable-array-range-checks

compiler/testData/codegen/box/binaryOp/eqNullableToPrimitiveWithSideEffects.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS, JS_IR, WASM
+// IGNORE_BACKEND: JS, JS_IR, JS_IR_ES6, WASM
 var result = ""
 
 fun sideEffecting(): Int {

compiler/testData/codegen/box/bridges/kt46389.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS, JS_IR
+// IGNORE_BACKEND: JS, JS_IR, JS_IR_ES6
 
 // The code in this test should be prohibited in the frontend, see KT-36188.
 

compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS, JS_IR
+// IGNORE_BACKEND: JS, JS_IR, JS_IR_ES6
 // !JVM_DEFAULT_MODE: all
 // JVM_TARGET: 1.8
 

compiler/testData/codegen/box/callableReference/funInterfaceConstructor/funInterfaceConstructedObjectsEquality.kt

@@ -7,7 +7,7 @@
 //  ^ wasm-function[1893]:0x1cf8a: RuntimeError: dereferencing a null pointer
 
 // IGNORE_BACKEND: JS
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 //  ^ TypeError: tmp is not a function
 
 // FILE: funInterfaceConstructedObjectsEquality.kt

compiler/testData/codegen/box/callableReference/funInterfaceConstructor/funInterfaceConstructorEquality.kt

@@ -7,7 +7,7 @@
 //  ^ Failed: ks1 != ks2 (same file, same SAM type)
 
 // IGNORE_BACKEND: JS
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 //  ^ Failed: ks1 != ks2 (same file, same SAM type)
 
 // FILE: funInterfaceConstructorEquality.kt

compiler/testData/codegen/box/casts/castToDefinitelyNotNullType.kt

@@ -1,6 +1,6 @@
 // !LANGUAGE: +DefinitelyNonNullableTypes
 // IGNORE_BACKEND: JS
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 // IGNORE_BACKEND: WASM
 
 fun <T> test(t: T) = t as (T & Any)

compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS, JS_IR, WASM
+// IGNORE_BACKEND: JS, JS_IR, JS_IR_ES6, WASM
 @Suppress("UNCHECKED_CAST")
 fun <T> f() = 1L as T
 

compiler/testData/codegen/box/classLiteral/primitiveClassEquality.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS, JS_IR, WASM
+// IGNORE_BACKEND: JS, JS_IR, JS_IR_ES6, WASM
 
 // boxed primitive comparisons
 fun isBoolean(a: Any) = a::class == true::class

compiler/testData/codegen/box/closures/captureInSuperConstructorCall/outerCapturedInPrimaryConstructorDefaultParameter.kt

@@ -1,5 +1,4 @@
-// IGNORE_BACKEND: JS_IR_ES6
-// IGNORE_BACKEND_K2: JS_IR
+// IGNORE_BACKEND_K2: JS_IR, JS_IR_ES6
 
 class Outer(val x: Any) {
     inner class Inner(

compiler/testData/codegen/box/closures/captureInSuperConstructorCall/outerCapturedInSecondaryConstructorDefaultParameter.kt

@@ -1,5 +1,4 @@
-// IGNORE_BACKEND: JS_IR_ES6
-// IGNORE_BACKEND_K2: JS_IR
+// IGNORE_BACKEND_K2: JS_IR, JS_IR_ES6
 
 class Outer(val x: Any) {
     inner class Inner(

compiler/testData/codegen/box/coroutines/inlineClasses/direct/boxReturnValueOfSuspendFunctionReference.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS_IR_ES6
 // WITH_STDLIB
 // WITH_COROUTINES
 

compiler/testData/codegen/box/coroutines/inlineClasses/direct/boxReturnValueOfSuspendLambda.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS_IR_ES6
 // WITH_STDLIB
 // WITH_COROUTINES
 

compiler/testData/codegen/box/coroutines/inlineClasses/resume/boxReturnValueOfSuspendFunctionReference.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS_IR_ES6
 // WITH_STDLIB
 // WITH_COROUTINES
 

compiler/testData/codegen/box/coroutines/inlineClasses/resume/boxReturnValueOfSuspendLambda.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS_IR_ES6
 // WITH_STDLIB
 // WITH_COROUTINES
 

compiler/testData/codegen/box/coroutines/inlineClasses/resumeWithException/boxReturnValueOfSuspendFunctionReference.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS_IR_ES6
 // WITH_STDLIB
 // WITH_COROUTINES
 

compiler/testData/codegen/box/coroutines/inlineClasses/resumeWithException/boxReturnValueOfSuspendLambda.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS_IR_ES6
 // WITH_STDLIB
 // WITH_COROUTINES
 

compiler/testData/codegen/box/coroutines/multiModule/inlineMultiModule.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 // WITH_COROUTINES
 // WITH_STDLIB
 // MODULE: lib(support)

compiler/testData/codegen/box/coroutines/multiModule/inlineMultiModuleOverride.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 // WITH_COROUTINES
 // WITH_STDLIB
 // MODULE: lib(support)

compiler/testData/codegen/box/coroutines/multiModule/inlineMultiModuleWithController.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 // KT-55464
 // IGNORE_BACKEND_K2: NATIVE
 // WITH_COROUTINES

compiler/testData/codegen/box/coroutines/multiModule/inlineMultiModuleWithInnerInlining.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 // WITH_COROUTINES
 // WITH_STDLIB
 // MODULE: lib(support)

compiler/testData/codegen/box/coroutines/suspendInTheMiddleOfObjectConstructionEvaluationOrder.kt

@@ -1,7 +1,6 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: NESTED_OBJECT_INIT
 // IGNORE_BACKEND: NATIVE
-// IGNORE_BACKEND: JS_IR_ES6
 // WITH_STDLIB
 // WITH_COROUTINES
 import helpers.*

compiler/testData/codegen/box/coroutines/varSpilling/lvtWithInlineOnly.kt

@@ -1,6 +1,6 @@
 // WITH_STDLIB
 // FULL_JDK
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 
 import kotlin.coroutines.*
 

compiler/testData/codegen/box/dataClasses/toString/primitiveArrays.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND: JVM, JS, JS_IR
+// IGNORE_BACKEND: JVM, JS, JS_IR, JS_IR_ES6
 // KT-30080
 
 data class A(

compiler/testData/codegen/box/delegatedProperty/delegateToSingleton/delegateToSingleton.kt

@@ -1,7 +1,7 @@
 // WITH_STDLIB
 // CHECK_BYTECODE_LISTING
 // FIR_IDENTICAL
-// IGNORE_BACKEND: JS_IR
+// IGNORE_BACKEND: JS_IR, JS_IR_ES6
 
 import kotlin.reflect.KProperty
 import kotlin.test.assertEquals

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/defaultArgsOverridden.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // IGNORE_FIR_DIAGNOSTICS_DIFF
 
 open class A {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/functionWithNoTails.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 
 <!NO_TAIL_CALLS_FOUND!>tailrec<!> fun noTails() {
     // nothing here

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/functionWithNonTailRecursions.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/insideElvis.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 // IGNORE_FIR_DIAGNOSTICS_DIFF

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/labeledThisReferences.kt

@@ -1,7 +1,6 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/loops.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 
 tailrec fun test(x : Int) : Int {
     var z = if (x > 3) 3 else x

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/multilevelBlocks.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/recursiveCallInLambda.kt

@@ -1,7 +1,6 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// IGNORE_BACKEND: JS_IR_ES6
 
 <!NO_TAIL_CALLS_FOUND!>tailrec<!> fun foo() {
     bar {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/recursiveCallInLocalFunction.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 
 <!NO_TAIL_CALLS_FOUND!>tailrec<!> fun foo() {
     fun bar() {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnIf.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnInCatch.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 
 <!NO_TAIL_CALLS_FOUND!>tailrec<!> fun test(counter : Int) : Int {
     if (counter == 0) return 0

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnInFinally.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 
 <!NO_TAIL_CALLS_FOUND!>tailrec<!> fun test(counter : Int) : Int {
     if (counter == 0) return 0

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnInIfInFinally.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 
 <!NO_TAIL_CALLS_FOUND!>tailrec<!> fun test(counter : Int) : Int {
     if (counter == 0) return 0

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/returnInTry.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 
 <!NO_TAIL_CALLS_FOUND!>tailrec<!> fun test(counter : Int) : Int {
     if (counter == 0) return 0

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/simpleBlock.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/simpleReturn.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/simpleReturnWithElse.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/tailRecursionInFinally.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 
 <!NO_TAIL_CALLS_FOUND!>tailrec<!> fun test(go: Boolean) : Unit {
     if (!go) return

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/tailrecWithExplicitCompanionObjectDispatcher.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // DONT_RUN_GENERATED_CODE: JS
 // IGNORE_BACKEND: JVM
 // IGNORE_FIR_DIAGNOSTICS_DIFF

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/tailrecWithExplicitObjectDispatcher.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JS_IR_ES6
 // DONT_RUN_GENERATED_CODE: JS
 
 object O {

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/thisReferences.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS
 

compiler/testData/codegen/box/diagnostics/functions/tailRecursion/unitBlocks.kt

@@ -1,6 +1,5 @@
 // IGNORE_BACKEND: WASM
 // WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR_ES6
 // TODO: muted automatically, investigate should it be ran for JS or not
 // IGNORE_BACKEND: JS