KT-4107 Data objects

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt

@@ -353,6 +353,7 @@ private val jvmFilePhases = listOf(
 
     enumClassPhase,
     objectClassPhase,
+    readResolveForDataObjectsPhase,
     staticInitializersPhase,
     initializersPhase,
     initializersCleanupPhase,

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/ReadResolveForDataObjectsLowering.kt

@@ -0,0 +1,63 @@
+/*
+ * 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.backend.jvm.lower
+
+import org.jetbrains.kotlin.backend.common.ClassLoweringPass
+import org.jetbrains.kotlin.backend.common.ir.addDispatchReceiver
+import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
+import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
+import org.jetbrains.kotlin.backend.jvm.ir.createJvmIrBuilder
+import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
+import org.jetbrains.kotlin.descriptors.Modality
+import org.jetbrains.kotlin.ir.builders.declarations.buildFun
+import org.jetbrains.kotlin.ir.builders.irExprBody
+import org.jetbrains.kotlin.ir.builders.irGetField
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
+import org.jetbrains.kotlin.ir.util.defaultType
+import org.jetbrains.kotlin.ir.util.fields
+import org.jetbrains.kotlin.ir.util.getAllSuperclasses
+import org.jetbrains.kotlin.ir.util.hasEqualFqName
+import org.jetbrains.kotlin.load.java.JvmAbi
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+
+internal val readResolveForDataObjectsPhase = makeIrFilePhase(
+    ::ReadResolveForDataObjectsLowering,
+    name = "ReadResolveForDataObjectsLowering",
+    description = "Generate readResolve for serializable data objects"
+)
+
+private class ReadResolveForDataObjectsLowering(val context: JvmBackendContext) : ClassLoweringPass {
+    override fun lower(irClass: IrClass) {
+        if (!context.state.languageVersionSettings.supportsFeature(LanguageFeature.DataObjects)) return
+
+        if (!irClass.isData || irClass.kind != ClassKind.OBJECT || !irClass.isSerializable()) return
+
+        context.irFactory.buildFun {
+            name = Name.identifier("readResolve")
+            modality = Modality.FINAL
+            origin = IrDeclarationOrigin.GENERATED_DATA_CLASS_MEMBER
+            returnType = context.irBuiltIns.anyType
+            visibility = DescriptorVisibilities.PRIVATE
+        }.apply {
+            addDispatchReceiver { type = irClass.defaultType }
+            parent = irClass
+            body = context.createJvmIrBuilder(symbol).run {
+                val instanceField = irClass.fields.single { it.name.asString() == JvmAbi.INSTANCE_FIELD }
+                irExprBody(irGetField(null, instanceField))
+            }
+            irClass.declarations.add(this)
+        }
+    }
+}
+
+private val SERIALIZABLE_FQ_NAME = FqName("java.io.Serializable")
+
+private fun IrClass.isSerializable(): Boolean =
+    getAllSuperclasses().any { it.hasEqualFqName(SERIALIZABLE_FQ_NAME) }