Objects (singletons) lowering.

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/DeclarationOrigins.kt

@@ -25,6 +25,7 @@ interface JvmLoweredDeclarationOrigin : IrDeclarationOrigin {
     object DEFAULT_IMPLS : IrDeclarationOriginImpl("DEFAULT_IMPL")
     object FIELD_FOR_ENUM_ENTRY : IrDeclarationOriginImpl("FIELD_FOR_ENUM_ENTRY")
     object FIELD_FOR_ENUM_VALUES : IrDeclarationOriginImpl("FIELD_FOR_ENUM_VALUES")
+    object FIELD_FOR_OBJECT_INSTANCE : IrDeclarationOriginImpl("FIELD_FOR_OBJECT_INSTANCE")
 }
 
 interface JvmLoweredStatementOrigin : IrStatementOrigin {

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

@@ -19,7 +19,6 @@ package org.jetbrains.kotlin.backend.jvm
 import org.jetbrains.kotlin.backend.jvm.lower.*
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrClass
-import org.jetbrains.kotlin.ir.declarations.IrDeclarationContainer
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.expressions.IrBody
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
@@ -34,6 +33,7 @@ class JvmLower(val context: JvmBackendContext) {
         InterfaceLowering(context.state).runOnFile(irFile)
         InterfaceDelegationLowering(context.state).runOnFile(irFile)
         EnumClassLowering(context).runOnFile(irFile)
+        ObjectClassLowering(context).runOnFile(irFile)
         InitializersLowering().runOnFile(irFile)
         SingletonReferencesLowering(context).runOnFile(irFile)
     }

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ClassCodegen.kt

@@ -18,6 +18,7 @@ package org.jetbrains.kotlin.backend.jvm.codegen
 
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
+import org.jetbrains.kotlin.backend.jvm.descriptors.JvmSpecialDescriptor
 import org.jetbrains.kotlin.backend.jvm.lower.FileClassDescriptor
 import org.jetbrains.kotlin.codegen.*
 import org.jetbrains.kotlin.codegen.MemberCodegen.badDescriptor
@@ -137,7 +138,13 @@ fun MemberDescriptor.calculateCommonFlags(): Int {
         throw RuntimeException("Unsupported visibility $visibility for descriptor $this")
     }
 
-    return flags.or(calcModalityFlag())
+    flags =  flags.or(calcModalityFlag())
+
+    if (this is JvmSpecialDescriptor) {
+        flags = flags or extraFlags
+    }
+
+    return flags
 }
 
 private fun MemberDescriptor.calcModalityFlag(): Int {

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/JvmSpecialDescriptor.kt

@@ -50,7 +50,7 @@ class JvmPropertyDescriptorImpl(
             )
 
     companion object {
-        fun createVal(
+        fun createStaticVal(
                 name: Name,
                 type: KotlinType,
                 containingDeclaration: DeclarationDescriptor,

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/SpecialDescriptorsFactory.kt

@@ -16,22 +16,24 @@
 
 package org.jetbrains.kotlin.backend.jvm.descriptors
 
-import org.jetbrains.kotlin.backend.jvm.descriptors.JvmPropertyDescriptorImpl
 import org.jetbrains.kotlin.backend.jvm.lower.FileClassDescriptor
 import org.jetbrains.kotlin.backend.jvm.lower.FileClassDescriptorImpl
 import org.jetbrains.kotlin.descriptors.*
+import org.jetbrains.kotlin.descriptors.annotations.Annotations
+import org.jetbrains.kotlin.descriptors.impl.PropertyDescriptorImpl
 import org.jetbrains.kotlin.fileClasses.JvmFileClassUtil
 import org.jetbrains.kotlin.ir.SourceManager
+import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi2ir.PsiSourceManager
 import org.jetbrains.kotlin.resolve.source.KotlinSourceElement
 import org.jetbrains.org.objectweb.asm.Opcodes
 import java.util.*
 
 class SpecialDescriptorsFactory(val psiSourceManager: PsiSourceManager) {
-    private val enumEntryFieldDescriptors = HashMap<ClassDescriptor, PropertyDescriptor>()
+    private val singletonFieldDescriptors = HashMap<ClassDescriptor, PropertyDescriptor>()
 
     fun getFieldDescriptorForEnumEntry(enumEntryDescriptor: ClassDescriptor): PropertyDescriptor =
-            enumEntryFieldDescriptors.getOrPut(enumEntryDescriptor) {
+            singletonFieldDescriptors.getOrPut(enumEntryDescriptor) {
                 createEnumEntryFieldDescriptor(enumEntryDescriptor)
             }
 
@@ -49,7 +51,7 @@ class SpecialDescriptorsFactory(val psiSourceManager: PsiSourceManager) {
         val enumClassDescriptor = enumEntryDescriptor.containingDeclaration as ClassDescriptor
         assert(enumClassDescriptor.kind == ClassKind.ENUM_CLASS) { "Should be enum class: $enumClassDescriptor"}
 
-        return JvmPropertyDescriptorImpl.createVal(
+        return JvmPropertyDescriptorImpl.createStaticVal(
                 enumEntryDescriptor.name,
                 enumClassDescriptor.defaultType,
                 enumClassDescriptor,
@@ -60,4 +62,23 @@ class SpecialDescriptorsFactory(val psiSourceManager: PsiSourceManager) {
                 enumEntryDescriptor.source
         )
     }
+
+    fun getFieldDescriptorForObjectInstance(objectDescriptor: ClassDescriptor): PropertyDescriptor =
+            singletonFieldDescriptors.getOrPut(objectDescriptor) {
+                createObjectInstanceFieldDescriptor(objectDescriptor)
+            }
+
+    private fun createObjectInstanceFieldDescriptor(objectDescriptor: ClassDescriptor): PropertyDescriptor {
+        assert(objectDescriptor.kind == ClassKind.OBJECT) { "Should be an object: $objectDescriptor" }
+
+        val instanceFieldDescriptor = PropertyDescriptorImpl.create(
+                objectDescriptor,
+                Annotations.EMPTY, Modality.FINAL, Visibilities.PUBLIC, false,
+                Name.identifier("INSTANCE"),
+                CallableMemberDescriptor.Kind.SYNTHESIZED, SourceElement.NO_SOURCE, false, false
+        )
+        instanceFieldDescriptor.setType(objectDescriptor.defaultType, listOf(), null as ReceiverParameterDescriptor?, null as ReceiverParameterDescriptor?)
+
+        return instanceFieldDescriptor
+    }
 }

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

@@ -246,7 +246,7 @@ class EnumClassLowering(val context: JvmBackendContext) : ClassLoweringPass {
                         })
 
         private fun createSyntheticValuesFieldDescriptor(valuesArrayType: SimpleType): PropertyDescriptorImpl {
-            return JvmPropertyDescriptorImpl.createVal(
+            return JvmPropertyDescriptorImpl.createStaticVal(
                     Name.identifier("\$VALUES"),
                     valuesArrayType,
                     irClass.descriptor,

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

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.backend.jvm.lower
+
+import org.jetbrains.kotlin.backend.jvm.ClassLoweringPass
+import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
+import org.jetbrains.kotlin.backend.jvm.JvmLoweredDeclarationOrigin
+import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.impl.IrFieldImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrExpressionBodyImpl
+
+class ObjectClassLowering(val context: JvmBackendContext) : ClassLoweringPass {
+    override fun lower(irClass: IrClass) {
+        if (irClass.descriptor.kind != ClassKind.OBJECT) return
+
+        val instanceFieldDescriptor = context.specialDescriptorsFactory.getFieldDescriptorForObjectInstance(irClass.descriptor)
+
+        val constructor = irClass.descriptor.unsubstitutedPrimaryConstructor ?:
+                          throw AssertionError("Object should have a primary constructor: ${irClass.descriptor}")
+        val instanceInitializer = IrCallImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, constructor)
+
+        val instanceField = IrFieldImpl(
+                UNDEFINED_OFFSET, UNDEFINED_OFFSET, JvmLoweredDeclarationOrigin.FIELD_FOR_OBJECT_INSTANCE,
+                instanceFieldDescriptor,
+                IrExpressionBodyImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, instanceInitializer)
+        )
+
+        irClass.declarations.add(instanceField)
+    }
+}

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

@@ -21,6 +21,7 @@ import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
 import org.jetbrains.kotlin.ir.expressions.IrBody
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.IrGetEnumValue
+import org.jetbrains.kotlin.ir.expressions.IrGetObjectValue
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetFieldImpl
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
@@ -34,4 +35,9 @@ class SingletonReferencesLowering(val context: JvmBackendContext) : BodyLowering
         val enumValueFieldDescriptor = context.specialDescriptorsFactory.getFieldDescriptorForEnumEntry(expression.descriptor)
         return IrGetFieldImpl(expression.startOffset, expression.endOffset, enumValueFieldDescriptor)
     }
+
+    override fun visitGetObjectValue(expression: IrGetObjectValue): IrExpression {
+        val instanceFieldDescriptor = context.specialDescriptorsFactory.getFieldDescriptorForObjectInstance(expression.descriptor)
+        return IrGetFieldImpl(expression.startOffset, expression.endOffset, instanceFieldDescriptor)
+    }
 }

compiler/testData/ir/box/objectClass.kt

@@ -0,0 +1,6 @@
+object Test {
+    val ok = "OK"
+}
+
+fun box(): String =
+        Test.ok

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrOnlyBoxCodegenTestGenerated.java

@@ -52,4 +52,10 @@ public class IrOnlyBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTest
         String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/box/fileClassInitializers.kt");
         doTest(fileName);
     }
+
+    @TestMetadata("objectClass.kt")
+    public void testObjectClass() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/box/objectClass.kt");
+        doTest(fileName);
+    }
 }