[Interop] Generate IR for CEnum inheritors

Since there is non-trivial logic inside code that we generate for interop enums, we generate it inside special IrProvider.

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ToplevelPhases.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.backend.konan.descriptors.isForwardDeclarationModule
 import org.jetbrains.kotlin.backend.konan.descriptors.konanLibrary
 import org.jetbrains.kotlin.backend.konan.ir.interop.IrProviderForInteropStubs
 import org.jetbrains.kotlin.backend.konan.ir.KonanSymbols
+import org.jetbrains.kotlin.backend.konan.ir.interop.IrProviderForCEnumStubs
 import org.jetbrains.kotlin.backend.konan.llvm.*
 import org.jetbrains.kotlin.backend.konan.lower.ExpectToActualDefaultValueCopier
 import org.jetbrains.kotlin.backend.konan.objcexport.ObjCExport
@@ -201,14 +202,16 @@ internal val psiToIrPhase = konanUnitPhase(
 
             val functionIrClassFactory = BuiltInFictitiousFunctionIrClassFactory(
                     symbolTable, generatorContext.irBuiltIns, reflectionTypes)
-            // TODO: Add special handling for enums and structs.
-            val irProviderForInteropStubs = IrProviderForInteropStubs { false }
             val symbols = KonanSymbols(this, symbolTable, symbolTable.lazyWrapper, functionIrClassFactory)
             val stubGenerator = DeclarationStubGenerator(
                     moduleDescriptor, symbolTable,
                     config.configuration.languageVersionSettings
             )
-            val irProviders = listOf(irProviderForInteropStubs, functionIrClassFactory, deserializer, stubGenerator)
+            val irProviderForCEnums = IrProviderForCEnumStubs(generatorContext, interopBuiltIns, stubGenerator, symbols)
+            val irProviderForInteropStubs = IrProviderForInteropStubs { symbol ->
+                irProviderForCEnums.canHandleSymbol(symbol)
+            }
+            val irProviders = listOf(irProviderForCEnums, irProviderForInteropStubs, functionIrClassFactory, deserializer, stubGenerator)
             stubGenerator.setIrProviders(irProviders)
 
             expectDescriptorToSymbol = mutableMapOf<DeclarationDescriptor, IrSymbol>()
@@ -236,6 +239,8 @@ internal val psiToIrPhase = konanUnitPhase(
             functionIrClassFactory.module =
                     (listOf(irModule!!) + deserializer.modules.values)
                             .single { it.descriptor.isKonanStdlib() }
+
+            irProviderForCEnums.module = module
         },
         name = "Psi2Ir",
         description = "Psi to IR conversion",

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/interop/DescriptorToIrTranslationUtils.kt

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+package org.jetbrains.kotlin.backend.konan.ir.interop
+
+import org.jetbrains.kotlin.backend.common.ir.createParameterDeclarations
+import org.jetbrains.kotlin.backend.konan.InteropBuiltIns
+import org.jetbrains.kotlin.descriptors.*
+import org.jetbrains.kotlin.ir.builders.IrBuilder
+import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.impl.IrInstanceInitializerCallImpl
+import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbol
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.resolve.descriptorUtil.getSuperInterfaces
+import org.jetbrains.kotlin.resolve.descriptorUtil.parentsWithSelf
+import org.jetbrains.kotlin.types.KotlinType
+
+internal inline fun <reified T: DeclarationDescriptor> ClassDescriptor.findDeclarationByName(name: String): T? =
+        unsubstitutedMemberScope
+                .getContributedDescriptors()
+                .filterIsInstance<T>()
+                .firstOrNull { it.name.identifier == name }
+
+/**
+ * Provides a set of functions and properties that helps
+ * to translate descriptor declarations to corresponding IR.
+ */
+internal interface DescriptorToIrTranslationMixin {
+
+    val symbolTable: SymbolTable
+
+    val irBuiltIns: IrBuiltIns
+
+    val typeTranslator: TypeTranslator
+
+    val stubGenerator: DeclarationStubGenerator
+
+    fun KotlinType.toIrType() = typeTranslator.translateType(this)
+
+    /**
+     * Declares [IrClass] instance from [descriptor] and populates it with
+     * supertypes, <this> parameter declaration and fake overrides.
+     * Additional elements are passed via [builder] callback.
+     */
+    fun createClass(descriptor: ClassDescriptor, builder: (IrClass) -> Unit): IrClass =
+            symbolTable.declareClass(
+                    startOffset = SYNTHETIC_OFFSET,
+                    endOffset = SYNTHETIC_OFFSET,
+                    origin = IrDeclarationOrigin.IR_EXTERNAL_DECLARATION_STUB,
+                    descriptor = descriptor
+            ).also { irClass ->
+                symbolTable.withScope(descriptor) {
+                    descriptor.typeConstructor.supertypes.mapTo(irClass.superTypes) {
+                        it.toIrType()
+                    }
+                    irClass.createParameterDeclarations()
+                    builder(irClass)
+                    createFakeOverrides(descriptor).forEach(irClass::addMember)
+                }
+            }
+
+    private fun createFakeOverrides(classDescriptor: ClassDescriptor): List<IrDeclaration> {
+        val fakeOverrides = classDescriptor.unsubstitutedMemberScope
+                .getContributedDescriptors()
+                .filterIsInstance<CallableMemberDescriptor>()
+                .filter { it.kind == CallableMemberDescriptor.Kind.FAKE_OVERRIDE }
+        return fakeOverrides.map {
+            when (it) {
+                is PropertyDescriptor -> createProperty(it)
+                is FunctionDescriptor -> createFunction(it, IrDeclarationOrigin.FAKE_OVERRIDE)
+                else -> error("Unexpected fake override descriptor: $it")
+            } as IrDeclaration // Assistance for type inference.
+        }
+    }
+
+    fun createConstructor(constructorDescriptor: ClassConstructorDescriptor): IrConstructor =
+            stubGenerator.generateMemberStub(constructorDescriptor) as IrConstructor
+
+    fun createProperty(propertyDescriptor: PropertyDescriptor): IrProperty =
+            stubGenerator.generateMemberStub(propertyDescriptor) as IrProperty
+
+    fun createFunction(
+            functionDescriptor: FunctionDescriptor,
+            origin: IrDeclarationOrigin? = IrDeclarationOrigin.IR_EXTERNAL_DECLARATION_STUB
+    ): IrSimpleFunction =
+            stubGenerator.generateFunctionStub(functionDescriptor, createPropertyIfNeeded = false).also {
+                if (origin != null) it.origin = origin
+            }
+}
+
+internal fun IrBuilder.irInstanceInitializer(classSymbol: IrClassSymbol): IrExpression =
+        IrInstanceInitializerCallImpl(
+                startOffset, endOffset,
+                classSymbol,
+                context.irBuiltIns.unitType
+        )
+
+internal fun ClassDescriptor.implementsCEnum(interopBuiltIns: InteropBuiltIns): Boolean =
+        interopBuiltIns.cEnum in this.getSuperInterfaces()
+
+/**
+ * All enums that come from interop library implement CEnum interface.
+ * This function checks that given symbol located in subtree of
+ * CEnum inheritor.
+ */
+internal fun IrSymbol.findCEnumDescriptor(interopBuiltIns: InteropBuiltIns): ClassDescriptor? =
+        descriptor.parentsWithSelf
+                .filterIsInstance<ClassDescriptor>()
+                .firstOrNull { it.implementsCEnum(interopBuiltIns) }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/interop/IrProviderForCEnumStubs.kt

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+package org.jetbrains.kotlin.backend.konan.ir.interop
+
+import org.jetbrains.kotlin.backend.konan.InteropBuiltIns
+import org.jetbrains.kotlin.backend.konan.descriptors.findPackage
+import org.jetbrains.kotlin.backend.konan.descriptors.isFromInteropLibrary
+import org.jetbrains.kotlin.backend.konan.ir.KonanSymbols
+import org.jetbrains.kotlin.backend.konan.ir.interop.cenum.CEnumByValueFunctionGenerator
+import org.jetbrains.kotlin.backend.konan.ir.interop.cenum.CEnumClassGenerator
+import org.jetbrains.kotlin.backend.konan.ir.interop.cenum.CEnumCompanionGenerator
+import org.jetbrains.kotlin.backend.konan.ir.interop.cenum.CEnumVarClassGenerator
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.PackageFragmentDescriptor
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.declarations.IrDeclarationContainer
+import org.jetbrains.kotlin.ir.declarations.IrFile
+import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
+import org.jetbrains.kotlin.ir.declarations.impl.IrFileImpl
+import org.jetbrains.kotlin.ir.symbols.*
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.psi2ir.generators.GeneratorContext
+import org.jetbrains.kotlin.resolve.descriptorUtil.module
+
+/**
+ * For the most of descriptors that come from metadata-based interop libraries
+ * we generate a lazy IR.
+ * We use a different approach for CEnums and generate IR eagerly. Motivation:
+ * 1. CEnums are "real" Kotlin enums. Thus, we need apply the same compilation approach
+ *   as we use for usual Kotlin enums.
+ *   Eager generation allows to reuse [EnumClassLowering], [EnumConstructorsLowering] and other
+ *   compiler phases.
+ * 2. It is an easier and more obvious approach. Since implementation of metadata-based
+ *  libraries generation already took too much time we take an easier approach here.
+ */
+internal class IrProviderForCEnumStubs(
+        context: GeneratorContext,
+        private val interopBuiltIns: InteropBuiltIns,
+        stubGenerator: DeclarationStubGenerator,
+        symbols: KonanSymbols
+) : IrProvider {
+
+    private val symbolTable: SymbolTable = context.symbolTable
+
+    private val filesMap = mutableMapOf<PackageFragmentDescriptor, IrFile>()
+
+    private val cEnumByValueFunctionGenerator =
+            CEnumByValueFunctionGenerator(context, stubGenerator, symbols)
+    private val cEnumCompanionGenerator =
+            CEnumCompanionGenerator(context, stubGenerator, cEnumByValueFunctionGenerator)
+    private val cEnumVarClassGenerator =
+            CEnumVarClassGenerator(context, stubGenerator, interopBuiltIns)
+    private val cEnumClassGenerator =
+            CEnumClassGenerator(context, stubGenerator, cEnumCompanionGenerator, cEnumVarClassGenerator)
+
+    var module: IrModuleFragment? = null
+        set(value) {
+            if (value == null)
+                error("Provide a valid non-null module")
+            if (field != null)
+                error("Module has already been set")
+            field = value
+            value.files += filesMap.values
+        }
+
+    fun canHandleSymbol(symbol: IrSymbol): Boolean {
+        if (!symbol.descriptor.module.isFromInteropLibrary()) return false
+        return symbol.findCEnumDescriptor(interopBuiltIns) != null
+    }
+
+    override fun getDeclaration(symbol: IrSymbol): IrDeclaration? {
+        if (symbol.isBound) return symbol.owner as IrDeclaration
+        if (!canHandleSymbol(symbol)) return null
+
+        val enumClassDescriptor = symbol.findCEnumDescriptor(interopBuiltIns)!!
+        // TODO: This call generates a whole subtree. This a simple but clearly suboptimal solution.
+        cEnumClassGenerator.findOrGenerateCEnum(enumClassDescriptor, irParentFor(enumClassDescriptor))
+        return when (symbol) {
+            is IrClassSymbol -> symbolTable.referenceClass(symbol.descriptor).owner
+            is IrEnumEntrySymbol -> symbolTable.referenceEnumEntry(symbol.descriptor).owner
+            is IrFunctionSymbol -> symbolTable.referenceFunction(symbol.descriptor).owner
+            is IrPropertySymbol -> symbolTable.referenceProperty(symbol.descriptor).owner
+            else -> error(symbol)
+        }
+    }
+
+    private fun irParentFor(descriptor: ClassDescriptor): IrDeclarationContainer {
+        val packageFragmentDescriptor = descriptor.findPackage()
+        return filesMap.getOrPut(packageFragmentDescriptor) {
+            IrFileImpl(NaiveSourceBasedFileEntryImpl("CEnums"), packageFragmentDescriptor).also {
+                this@IrProviderForCEnumStubs.module?.files?.add(it)
+            }
+        }
+    }
+}

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/interop/cenum/CEnumByValueFunctionGenerator.kt

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+package org.jetbrains.kotlin.backend.konan.ir.interop.cenum
+
+import org.jetbrains.kotlin.backend.konan.ir.KonanSymbols
+import org.jetbrains.kotlin.backend.konan.ir.interop.DescriptorToIrTranslationMixin
+import org.jetbrains.kotlin.backend.konan.ir.interop.findDeclarationByName
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.ir.builders.*
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
+import org.jetbrains.kotlin.ir.types.classOrNull
+import org.jetbrains.kotlin.ir.types.getClass
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.util.irCall
+import org.jetbrains.kotlin.psi2ir.generators.GeneratorContext
+
+/**
+ * Generate IR for function that returns appropriate enum entry for the provided integral value.
+ */
+internal class CEnumByValueFunctionGenerator(
+        context: GeneratorContext,
+        override val stubGenerator: DeclarationStubGenerator,
+        private val symbols: KonanSymbols
+) : DescriptorToIrTranslationMixin {
+
+    override val irBuiltIns: IrBuiltIns = context.irBuiltIns
+    override val symbolTable: SymbolTable = context.symbolTable
+    override val typeTranslator: TypeTranslator = context.typeTranslator
+
+    fun generateByValueFunction(
+            companionIrClass: IrClass,
+            valuesIrFunctionSymbol: IrSimpleFunctionSymbol
+    ): IrFunction {
+        val byValueFunctionDescriptor = companionIrClass.descriptor.findDeclarationByName<FunctionDescriptor>("byValue")!!
+        val byValueIrFunction = createFunction(byValueFunctionDescriptor)
+        val irValueParameter = byValueIrFunction.valueParameters.first()
+        // val values: Array<E> = values()
+        // var i: Int = 0
+        // val size: Int = values.size
+        // while (i < size) {
+        //      val entry: E = values[i]
+        //      if (entry.value == arg) {
+        //          return entry
+        //      }
+        //      i++
+        // }
+        // throw NPE
+        byValueIrFunction.body = irBuilder(irBuiltIns, byValueIrFunction.symbol, SYNTHETIC_OFFSET, SYNTHETIC_OFFSET).irBlockBody {
+            +irReturn(irBlock {
+                val values = irTemporaryVar(irCall(valuesIrFunctionSymbol))
+                val inductionVariable = irTemporaryVar(irInt(0))
+                val arrayClass = values.type.classOrNull!!
+                val valuesSize = irCall(symbols.arraySize.getValue(arrayClass)).also { irCall ->
+                    irCall.dispatchReceiver = irGet(values)
+                }
+                val getElementFn = symbols.arrayGet.getValue(arrayClass)
+                val plusFun = symbols.intPlusInt
+                val lessFunctionSymbol = irBuiltIns.lessFunByOperandType.getValue(irBuiltIns.intClass)
+                +irWhile().also { loop ->
+                    loop.condition = irCall(lessFunctionSymbol).also { irCall ->
+                        irCall.putValueArgument(0, irGet(inductionVariable))
+                        irCall.putValueArgument(1, valuesSize)
+                    }
+                    loop.body = irBlock {
+                        val untypedEntry = irCall(getElementFn).also { irCall ->
+                            irCall.dispatchReceiver = irGet(values)
+                            irCall.putValueArgument(0, irGet(inductionVariable))
+                        }
+                        val entry = irTemporaryVar(irImplicitCast(untypedEntry, byValueIrFunction.returnType))
+                        val valueGetter = entry.type.getClass()!!.getPropertyGetter("value")!!
+                        val entryValue = irGet(irValueParameter.type, irGet(entry), valueGetter)
+                        +irIfThenElse(
+                                type = irBuiltIns.unitType,
+                                condition = irEquals(entryValue, irGet(irValueParameter)),
+                                thenPart = irReturn(irGet(entry)),
+                                elsePart = irSetVar(
+                                        inductionVariable,
+                                        irCallOp(plusFun, irBuiltIns.intType,
+                                                irGet(inductionVariable),
+                                                irInt(1)
+                                        )
+                                )
+                        )
+                    }
+                }
+                +irCall(symbols.ThrowNullPointerException)
+            })
+        }
+        return byValueIrFunction
+    }
+}

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/interop/cenum/CEnumClassGenerator.kt

@@ -0,0 +1,166 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+package org.jetbrains.kotlin.backend.konan.ir.interop.cenum
+
+import org.jetbrains.kotlin.backend.konan.descriptors.enumEntries
+import org.jetbrains.kotlin.backend.konan.ir.interop.DescriptorToIrTranslationMixin
+import org.jetbrains.kotlin.backend.konan.ir.interop.findDeclarationByName
+import org.jetbrains.kotlin.backend.konan.ir.interop.irInstanceInitializer
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.descriptors.PropertyDescriptor
+import org.jetbrains.kotlin.descriptors.Visibilities
+import org.jetbrains.kotlin.ir.builders.*
+import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.impl.IrEnumConstructorCallImpl
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.psi2ir.generators.DeclarationGenerator
+import org.jetbrains.kotlin.psi2ir.generators.EnumClassMembersGenerator
+import org.jetbrains.kotlin.psi2ir.generators.GeneratorContext
+import org.jetbrains.kotlin.resolve.constants.ConstantValue
+import org.jetbrains.kotlin.utils.addToStdlib.firstNotNullResult
+
+private fun extractConstantValue(descriptor: DeclarationDescriptor, type: String): ConstantValue<*>? =
+        descriptor.annotations
+                .findAnnotation(cEnumEntryValueAnnotationName.child(Name.identifier(type)))
+                ?.allValueArguments
+                ?.getValue(Name.identifier("value"))
+
+private val cEnumEntryValueAnnotationName = FqName("kotlinx.cinterop.internal.ConstantValue")
+
+private val cEnumEntryValueTypes = setOf(
+        "Byte", "Short", "Int", "Long",
+        "UByte", "UShort", "UInt", "ULong"
+)
+
+internal class CEnumClassGenerator(
+        val context: GeneratorContext,
+        override val stubGenerator: DeclarationStubGenerator,
+        private val cEnumCompanionGenerator: CEnumCompanionGenerator,
+        private val cEnumVarClassGenerator: CEnumVarClassGenerator
+) : DescriptorToIrTranslationMixin {
+
+    override val irBuiltIns: IrBuiltIns = context.irBuiltIns
+    override val symbolTable: SymbolTable = context.symbolTable
+    override val typeTranslator: TypeTranslator = context.typeTranslator
+
+    private val enumClassMembersGenerator = EnumClassMembersGenerator(DeclarationGenerator(context))
+
+    /**
+     * Searches for an IR class for [classDescriptor] in symbol table.
+     * Generates one if absent.
+     */
+    fun findOrGenerateCEnum(classDescriptor: ClassDescriptor, parent: IrDeclarationContainer): IrClass {
+        val irClassSymbol = symbolTable.referenceClass(classDescriptor)
+        return if (!irClassSymbol.isBound) {
+            provideIrClassForCEnum(classDescriptor).also {
+                it.patchDeclarationParents(parent)
+                parent.declarations += it
+            }
+        } else {
+            irClassSymbol.owner
+        }
+    }
+
+    /**
+     * The main function that for given [descriptor] of the enum generates the whole
+     * IR tree including entries, CEnumVar class, and companion objects.
+     */
+    private fun provideIrClassForCEnum(descriptor: ClassDescriptor): IrClass =
+            createClass(descriptor) { enumIrClass ->
+                enumIrClass.addMember(createEnumPrimaryConstructor(descriptor))
+                enumIrClass.addMember(createValueProperty(enumIrClass))
+                descriptor.enumEntries.mapTo(enumIrClass.declarations) { entryDescriptor ->
+                    createEnumEntry(descriptor, entryDescriptor)
+                }
+                enumClassMembersGenerator.generateSpecialMembers(enumIrClass)
+                enumIrClass.addChild(cEnumCompanionGenerator.generate(enumIrClass))
+                enumIrClass.addChild(cEnumVarClassGenerator.generate(enumIrClass))
+            }
+
+    /**
+     * Creates `value` property that stores integral value of the enum.
+     */
+    private fun createValueProperty(irClass: IrClass): IrProperty {
+        val propertyDescriptor = irClass.descriptor
+                .findDeclarationByName<PropertyDescriptor>("value")
+                ?: error("No `value` property in ${irClass.name}")
+        val irProperty = createProperty(propertyDescriptor)
+        symbolTable.withScope(propertyDescriptor) {
+            irProperty.backingField = symbolTable.declareField(
+                    SYNTHETIC_OFFSET, SYNTHETIC_OFFSET, IrDeclarationOrigin.PROPERTY_BACKING_FIELD,
+                    propertyDescriptor, propertyDescriptor.type.toIrType(), Visibilities.PRIVATE
+            ).also {
+                it.initializer = irBuilder(irBuiltIns, it.symbol, SYNTHETIC_OFFSET, SYNTHETIC_OFFSET).run {
+                    irExprBody(irGet(irClass.primaryConstructor!!.valueParameters[0]))
+                }
+            }
+            irProperty.getter = createFunction(
+                    propertyDescriptor.getter!!,
+                    IrDeclarationOrigin.DEFAULT_PROPERTY_ACCESSOR
+            ).also { getter ->
+                getter.correspondingPropertySymbol = irProperty.symbol
+                getter.body = irBuilder(irBuiltIns, getter.symbol, SYNTHETIC_OFFSET, SYNTHETIC_OFFSET).irBlockBody {
+                    +irReturn(
+                            irGetField(
+                                    irGet(getter.dispatchReceiverParameter!!),
+                                    irProperty.backingField!!
+                            )
+                    )
+                }
+            }
+        }
+        return irProperty
+    }
+
+    private fun createEnumEntry(enumDescriptor: ClassDescriptor, entryDescriptor: ClassDescriptor): IrEnumEntry {
+        return symbolTable.declareEnumEntry(
+                SYNTHETIC_OFFSET, SYNTHETIC_OFFSET,
+                IrDeclarationOrigin.IR_EXTERNAL_DECLARATION_STUB, entryDescriptor
+        ).also { enumEntry ->
+            enumEntry.initializerExpression = IrEnumConstructorCallImpl(
+                    SYNTHETIC_OFFSET, SYNTHETIC_OFFSET,
+                    type = irBuiltIns.unitType,
+                    symbol = symbolTable.referenceConstructor(enumDescriptor.unsubstitutedPrimaryConstructor!!),
+                    typeArgumentsCount = 0 // enums can't be generic
+            ).also {
+                it.putValueArgument(0, extractEnumEntryValue(entryDescriptor))
+            }
+        }
+    }
+
+    /**
+     * Every enum entry that came from metadata-based interop library is annotated with
+     * [kotlinx.cinterop.internal.ConstantValue] annotation that holds internal constant value of the
+     * corresponding entry.
+     *
+     * This function extracts value from the annotation.
+     */
+    private fun extractEnumEntryValue(entryDescriptor: ClassDescriptor): IrExpression =
+            cEnumEntryValueTypes.firstNotNullResult { extractConstantValue(entryDescriptor, it) } ?.let {
+                context.constantValueGenerator.generateConstantValueAsExpression(SYNTHETIC_OFFSET, SYNTHETIC_OFFSET, it)
+            } ?: error("Enum entry $entryDescriptor has no appropriate @$cEnumEntryValueAnnotationName annotation!")
+
+    private fun createEnumPrimaryConstructor(descriptor: ClassDescriptor): IrConstructor {
+        val irConstructor = createConstructor(descriptor.unsubstitutedPrimaryConstructor!!)
+        val enumConstructor = context.builtIns.enum.constructors.single()
+        irConstructor.body = irBuilder(irBuiltIns, irConstructor.symbol, SYNTHETIC_OFFSET, SYNTHETIC_OFFSET).irBlockBody {
+            +IrEnumConstructorCallImpl(
+                    startOffset, endOffset,
+                    context.irBuiltIns.unitType,
+                    symbolTable.referenceConstructor(enumConstructor),
+                    typeArgumentsCount = 1 // kotlin.Enum<T> has a single type parameter.
+            ).apply {
+                putTypeArgument(0, descriptor.defaultType.toIrType())
+            }
+            +irInstanceInitializer(symbolTable.referenceClass(descriptor))
+        }
+        return irConstructor
+    }
+}

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/interop/cenum/CEnumCompanionGenerator.kt

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+package org.jetbrains.kotlin.backend.konan.ir.interop.cenum
+
+import org.jetbrains.kotlin.backend.konan.descriptors.getArgumentValueOrNull
+import org.jetbrains.kotlin.backend.konan.ir.interop.DescriptorToIrTranslationMixin
+import org.jetbrains.kotlin.backend.konan.ir.interop.irInstanceInitializer
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.PropertyDescriptor
+import org.jetbrains.kotlin.ir.builders.irBlockBody
+import org.jetbrains.kotlin.ir.builders.irReturn
+import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.expressions.IrBody
+import org.jetbrains.kotlin.ir.expressions.impl.IrDelegatingConstructorCallImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrGetEnumValueImpl
+import org.jetbrains.kotlin.ir.symbols.IrEnumEntrySymbol
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.psi2ir.generators.GeneratorContext
+import org.jetbrains.kotlin.resolve.descriptorUtil.builtIns
+
+private val cEnumEntryAliasAnnonation = FqName("kotlinx.cinterop.internal.CEnumEntryAlias")
+
+internal class CEnumCompanionGenerator(
+        context: GeneratorContext,
+        override val stubGenerator: DeclarationStubGenerator,
+        private val cEnumByValueFunctionGenerator: CEnumByValueFunctionGenerator
+) : DescriptorToIrTranslationMixin {
+
+    override val irBuiltIns: IrBuiltIns = context.irBuiltIns
+    override val symbolTable: SymbolTable = context.symbolTable
+    override val typeTranslator: TypeTranslator = context.typeTranslator
+
+    // Depends on already generated `.values()` irFunction.
+    fun generate(enumClass: IrClass): IrClass =
+            createClass(enumClass.descriptor.companionObjectDescriptor!!) { companionIrClass ->
+                companionIrClass.superTypes += irBuiltIns.anyType
+                companionIrClass.addMember(createCompanionConstructor(companionIrClass.descriptor))
+                val valuesFunction = enumClass.functions.single { it.name.identifier == "values" }.symbol
+                val byValueIrFunction = cEnumByValueFunctionGenerator
+                        .generateByValueFunction(companionIrClass, valuesFunction)
+                companionIrClass.addMember(byValueIrFunction)
+                findEntryAliases(companionIrClass.descriptor)
+                        .map { declareEntryAliasProperty(it, enumClass) }
+                        .forEach(companionIrClass::addMember)
+            }
+
+    private fun createCompanionConstructor(companionObjectDescriptor: ClassDescriptor): IrConstructor {
+        val anyPrimaryConstructor = companionObjectDescriptor.builtIns.any.unsubstitutedPrimaryConstructor!!
+        val superConstructorSymbol = symbolTable.referenceConstructor(anyPrimaryConstructor)
+        return createConstructor(companionObjectDescriptor.unsubstitutedPrimaryConstructor!!).also {
+            it.body = irBuilder(irBuiltIns, it.symbol, SYNTHETIC_OFFSET, SYNTHETIC_OFFSET).irBlockBody {
+                +IrDelegatingConstructorCallImpl(
+                        startOffset, endOffset, context.irBuiltIns.unitType,
+                        superConstructorSymbol
+                )
+                +irInstanceInitializer(symbolTable.referenceClass(companionObjectDescriptor))
+            }
+        }
+    }
+
+    /**
+     * Returns all properties in companion object that represent aliases to
+     * enum entries.
+     */
+    private fun findEntryAliases(companionDescriptor: ClassDescriptor) =
+            companionDescriptor.defaultType.memberScope.getContributedDescriptors()
+                    .filterIsInstance<PropertyDescriptor>()
+                    .filter { it.annotations.hasAnnotation(cEnumEntryAliasAnnonation) }
+
+    private fun fundCorrespondingEnumEntrySymbol(aliasDescriptor: PropertyDescriptor, irClass: IrClass): IrEnumEntrySymbol {
+        val enumEntryName = aliasDescriptor.annotations
+                .findAnnotation(cEnumEntryAliasAnnonation)!!
+                .getArgumentValueOrNull<String>("entryName")
+        return irClass.declarations.filterIsInstance<IrEnumEntry>()
+                .single { it.name.identifier == enumEntryName }.symbol
+    }
+
+    private fun generateAliasGetterBody(getter: IrSimpleFunction, entrySymbol: IrEnumEntrySymbol): IrBody =
+            irBuilder(irBuiltIns, getter.symbol, SYNTHETIC_OFFSET, SYNTHETIC_OFFSET).irBlockBody {
+                +irReturn(
+                        IrGetEnumValueImpl(startOffset, endOffset, entrySymbol.owner.parentAsClass.defaultType, entrySymbol)
+                )
+            }
+
+    private fun declareEntryAliasProperty(propertyDescriptor: PropertyDescriptor, enumClass: IrClass): IrProperty {
+        val entrySymbol = fundCorrespondingEnumEntrySymbol(propertyDescriptor, enumClass)
+        return createProperty(propertyDescriptor).also {
+            it.getter!!.body = generateAliasGetterBody(it.getter!!, entrySymbol)
+        }
+    }
+}

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/interop/cenum/CEnumVarClassGenerator.kt

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+package org.jetbrains.kotlin.backend.konan.ir.interop.cenum
+
+import org.jetbrains.kotlin.backend.konan.InteropBuiltIns
+import org.jetbrains.kotlin.backend.konan.descriptors.getArgumentValueOrNull
+import org.jetbrains.kotlin.backend.konan.ir.interop.DescriptorToIrTranslationMixin
+import org.jetbrains.kotlin.backend.konan.ir.interop.irInstanceInitializer
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.incremental.components.NoLookupLocation
+import org.jetbrains.kotlin.ir.builders.irBlockBody
+import org.jetbrains.kotlin.ir.builders.irGet
+import org.jetbrains.kotlin.ir.builders.irInt
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrConstructor
+import org.jetbrains.kotlin.ir.declarations.IrProperty
+import org.jetbrains.kotlin.ir.declarations.addMember
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.expressions.impl.IrDelegatingConstructorCallImpl
+import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.psi2ir.generators.GeneratorContext
+
+private val typeSizeAnnotation = FqName("kotlinx.cinterop.internal.CEnumVarTypeSize")
+
+internal class CEnumVarClassGenerator(
+        context: GeneratorContext,
+        override val stubGenerator: DeclarationStubGenerator,
+        private val interopBuiltIns: InteropBuiltIns
+) : DescriptorToIrTranslationMixin {
+
+    override val irBuiltIns: IrBuiltIns = context.irBuiltIns
+    override val symbolTable: SymbolTable = context.symbolTable
+    override val typeTranslator: TypeTranslator = context.typeTranslator
+
+    fun generate(enumIrClass: IrClass): IrClass {
+        val enumVarClassDescriptor = enumIrClass.descriptor.unsubstitutedMemberScope
+                .getContributedClassifier(Name.identifier("Var"), NoLookupLocation.FROM_BACKEND)!! as ClassDescriptor
+        return createClass(enumVarClassDescriptor) { enumVarClass ->
+            enumVarClass.addMember(createPrimaryConstructor(enumVarClass))
+            enumVarClass.addMember(createCompanionObject(enumVarClass))
+            enumVarClass.addMember(createValueProperty(enumVarClass))
+        }
+    }
+
+    private fun createValueProperty(enumVarClass: IrClass): IrProperty {
+        val valuePropertyDescriptor = enumVarClass.descriptor.unsubstitutedMemberScope
+                .getContributedVariables(Name.identifier("value"), NoLookupLocation.FROM_BACKEND).single()
+        return createProperty(valuePropertyDescriptor)
+    }
+
+    private fun createPrimaryConstructor(enumVarClass: IrClass): IrConstructor {
+        val irConstructor = createConstructor(enumVarClass.descriptor.unsubstitutedPrimaryConstructor!!)
+        val enumVarConstructorSymbol = symbolTable.referenceConstructor(
+                interopBuiltIns.cEnumVar.unsubstitutedPrimaryConstructor!!
+        )
+        irConstructor.body = irBuilder(irBuiltIns, irConstructor.symbol, SYNTHETIC_OFFSET, SYNTHETIC_OFFSET).irBlockBody {
+            +IrDelegatingConstructorCallImpl(
+                    startOffset, endOffset, context.irBuiltIns.unitType, enumVarConstructorSymbol
+            ).also {
+                it.putValueArgument(0, irGet(irConstructor.valueParameters[0]))
+            }
+            +irInstanceInitializer(symbolTable.referenceClass(enumVarClass.descriptor))
+        }
+        return irConstructor
+    }
+
+    private fun createCompanionObject(enumVarClass: IrClass): IrClass =
+            createClass(enumVarClass.descriptor.companionObjectDescriptor!!) { companionIrClass ->
+                val typeSize = companionIrClass.descriptor.annotations
+                        .findAnnotation(typeSizeAnnotation)!!
+                        .getArgumentValueOrNull<Int>("size")!!
+                companionIrClass.addMember(createCompanionConstructor(companionIrClass.descriptor, typeSize))
+            }
+
+    private fun createCompanionConstructor(companionObjectDescriptor: ClassDescriptor, typeSize: Int): IrConstructor {
+        val superConstructorSymbol = symbolTable.referenceConstructor(interopBuiltIns.cPrimitiveVarType.unsubstitutedPrimaryConstructor!!)
+        return createConstructor(companionObjectDescriptor.unsubstitutedPrimaryConstructor!!).also {
+            it.body = irBuilder(irBuiltIns, it.symbol, SYNTHETIC_OFFSET, SYNTHETIC_OFFSET).irBlockBody {
+                +IrDelegatingConstructorCallImpl(
+                        startOffset, endOffset, context.irBuiltIns.unitType,
+                        superConstructorSymbol
+                ).also {
+                    it.putValueArgument(0, irInt(typeSize))
+                }
+                +irInstanceInitializer(symbolTable.referenceClass(companionObjectDescriptor))
+            }
+        }
+    }
+}

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/ir/util/IrUtils2.kt

@@ -49,12 +49,17 @@ import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.typeUtil.immediateSupertypes
 import java.lang.reflect.Proxy
 
-internal fun irBuilder(irBuiltIns: IrBuiltIns, scopeOwnerSymbol: IrSymbol): IrBuilderWithScope =
+internal fun irBuilder(
+        irBuiltIns: IrBuiltIns,
+        scopeOwnerSymbol: IrSymbol,
+        startOffset: Int = UNDEFINED_OFFSET,
+        endOffset: Int = UNDEFINED_OFFSET
+): IrBuilderWithScope =
         object : IrBuilderWithScope(
                 IrGeneratorContextBase(irBuiltIns),
                 Scope(scopeOwnerSymbol),
-                UNDEFINED_OFFSET,
+                startOffset,
-                UNDEFINED_OFFSET
+                endOffset
         ) {}
 
 //TODO: delete file on next kotlin dependency update