Allow libraries to have empty ir/ component.

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

@@ -81,7 +81,7 @@ fun runTopLevelPhases(konanConfig: KonanConfig, environment: KotlinCoreEnvironme
             if (library == null) {
                 return@map null
             }
-            deserializer.deserializeIrModule(it, library.irHeader)
+            library.irHeader?.let { header -> deserializer.deserializeIrModule(it, header) }
         }.filterNotNull()
 
         val symbols = KonanSymbols(context, generatorContext.symbolTable, generatorContext.symbolTable.lazyWrapper)
@@ -117,11 +117,11 @@ fun runTopLevelPhases(konanConfig: KonanConfig, environment: KotlinCoreEnvironme
 
     phaser.phase(KonanPhase.SERIALIZER) {
         val declarationTable = DeclarationTable(context.irModule!!.irBuiltins, DescriptorTable())
-        val serializedIr = IrModuleSerializer(context, declarationTable/*, onlyForInlines = false*/).serializedIrModule(context.irModule!!)
+        val serializedIr = IrModuleSerializer(context, declarationTable).serializedIrModule(context.irModule!!)
 
         val serializer = KonanSerializationUtil(context, context.config.configuration.get(CommonConfigurationKeys.METADATA_VERSION)!!, declarationTable)
         context.serializedLinkData =
-            serializer.serializeModule(context.moduleDescriptor, serializedIr)
+            serializer.serializeModule(context.moduleDescriptor, if (!context.config.isInteropStubs) serializedIr else null)
     }
     phaser.phase(KonanPhase.BACKEND) {
         phaser.phase(KonanPhase.LOWER) {

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/library/impl/MetadataWriterImpl.kt

@@ -12,7 +12,7 @@ internal class MetadataWriterImpl(libraryLayout: KonanLibraryLayout): KonanLibra
 
     fun addLinkData(linkData: LinkData) {
         moduleHeaderFile.writeBytes(linkData.module)
-        wholeIrFile.writeBytes(linkData.ir!!.module)
+        linkData.ir?.let { irHeader.writeBytes(it.module) }
         linkData.fragments.forEachIndexed { index, it ->
             val packageFqName = linkData.fragmentNames[index]
             val shortName = packageFqName.substringAfterLast(".")
@@ -33,7 +33,7 @@ internal class MetadataWriterImpl(libraryLayout: KonanLibraryLayout): KonanLibra
                 visibleDeclarationFile(index)
             file.writeBytes(it.value)
         }
-        val lines = linkData.ir?.debugIndex.map { entry -> "${entry.key}: ${entry.value}" }
-        irIndex.writeLines(lines)
+        val lines = linkData.ir?.debugIndex?.map { entry -> "${entry.key}: ${entry.value}" }
+        if (lines != null) irIndex.writeLines(lines)
     }
 }

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

@@ -675,7 +675,7 @@ internal class InteropLoweringPart1(val context: Context) : IrBuildingTransforme
                     val companionObject = classDescriptor.companionObjectDescriptor ?:
                             error("native variable class $classDescriptor must have the companion object")
 
-                    builder.at(expression).irGetObject(symbolTable.referenceClass(companionObject))
+                    builder.at(expression).irGetObject(symbolTable.lazyWrapper.referenceClass(companionObject))
                 }
             }
             else -> expression

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

@@ -210,24 +210,27 @@ class KonanIrModuleDeserializer(
         val uniqId = UniqId(descriptorUniqId.index, isLocal = false)
         val topLevelKey = UniqIdKey(topLevelDescriptor.module, uniqId)
 
+        // This top level descriptor doesn't have a serialized IR declaration.
+        if (topLevelKey.moduleOfOrigin == null) return null
+
         reachableTopLevels.add(topLevelKey)
 
         do {
             val key = reachableTopLevels.first()
 
-            if (deserializedSymbols[key]?.isBound == true) {
+            if (deserializedSymbols[key]?.isBound == true ||
+                // The key.moduleOrigin is null for uniqIds that we haven't seen in any of the library headers.
+                // Just skip it for now and handle it elsewhere.
+                key.moduleOfOrigin == null) {
+
                 reachableTopLevels.remove(key)
+                deserializedTopLevels.add(key)
                 continue
             }
 
-            if (key.moduleOfOrigin != null) {
-                deserializedModuleDescriptor = key.moduleOfOrigin
-                val reachable = deserializeTopLevelDeclaration(key)
-                reversedFileIndex[key]!!.declarations.add(reachable)
-            } else {
-                // The key.moduleOrigin is null for uniqIds that we haven't seen in any of the library headers.
-                // Just skip it for now and handle it elsewhere.
-            }
+            deserializedModuleDescriptor = key.moduleOfOrigin
+            val reachable = deserializeTopLevelDeclaration(key)
+            reversedFileIndex[key]!!.declarations.add(reachable)
 
             reachableTopLevels.remove(key)
             deserializedTopLevels.add(key)

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

@@ -209,7 +209,7 @@ internal class KonanSerializationUtil(val context: Context, val metadataVersion:
                 .build()
     }
 
-    internal fun serializeModule(moduleDescriptor: ModuleDescriptor, serializedIr: SerializedIr): LinkData {
+    internal fun serializeModule(moduleDescriptor: ModuleDescriptor, serializedIr: SerializedIr?): LinkData {
         val libraryProto = KonanProtoBuf.LinkDataLibrary.newBuilder()
         libraryProto.moduleName = moduleDescriptor.name.asString()
         val fragments = mutableListOf<List<ByteArray>>()

shared/src/library/kotlin/org/jetbrains/kotlin/konan/library/KonanLibrary.kt

@@ -43,7 +43,7 @@ interface KonanLibrary {
     fun packageMetadataParts(fqName: String): Set<String>
     fun packageMetadata(fqName: String, partName: String): ByteArray
 
-    val irHeader: ByteArray
+    val irHeader: ByteArray?
     fun irDeclaration(index: Long, isLocal: Boolean): ByteArray
 }
 

shared/src/library/kotlin/org/jetbrains/kotlin/konan/library/KonanLibraryLayout.kt

@@ -50,7 +50,7 @@ interface KonanLibraryLayout {
         = File(irDir, "hidden_$declarationId.knd")
     fun visibleDeclarationFile(declarationId: String)
         = File(irDir, "visible_$declarationId.knd")
-    val wholeIrFile
+    val irHeader
         get() = File(irDir, "irHeaders.kni")
     val irIndex: File
         get() = File(irDir, "uniqIdTableDump.txt")

shared/src/library/kotlin/org/jetbrains/kotlin/konan/library/KonanMetadataReader.kt

@@ -3,6 +3,6 @@ package org.jetbrains.kotlin.konan.library
 interface MetadataReader {
     fun loadSerializedModule(libraryLayout: KonanLibraryLayout): ByteArray
     fun loadSerializedPackageFragment(libraryLayout: KonanLibraryLayout, fqName: String, partName: String): ByteArray
-    fun loadWholeIr(libraryLayout: KonanLibraryLayout): ByteArray
+    fun loadIrHeader(libraryLayout: KonanLibraryLayout): ByteArray
     fun loadIrDeclaraton(libraryLayout: KonanLibraryLayout, index: Long, isLocal: Boolean): ByteArray
 }

shared/src/library/kotlin/org/jetbrains/kotlin/konan/library/impl/DefaultMetadataReaderImpl.kt

@@ -11,8 +11,8 @@ internal object DefaultMetadataReaderImpl : MetadataReader {
     override fun loadSerializedPackageFragment(libraryLayout: KonanLibraryLayout, fqName: String, partName: String): ByteArray =
             libraryLayout.packageFragmentFile(fqName, partName).readBytes()
 
-    override fun loadWholeIr(libraryLayout: KonanLibraryLayout): ByteArray =
-            libraryLayout.wholeIrFile.readBytes()
+    override fun loadIrHeader(libraryLayout: KonanLibraryLayout): ByteArray =
+            libraryLayout.irHeader.readBytes()
 
     override fun loadIrDeclaraton(libraryLayout: KonanLibraryLayout, index: Long, isLocal: Boolean): ByteArray {
         val name = index.toULong().toString(16)

shared/src/library/kotlin/org/jetbrains/kotlin/konan/library/impl/KonanLibraryImpl.kt

@@ -84,7 +84,7 @@ class KonanLibraryImpl(
                 }
             }
 
-    override val irHeader: ByteArray by lazy { layout.inPlace {  metadataReader.loadWholeIr(it) }}
+    override val irHeader: ByteArray? by lazy { layout.inPlace { library -> library.irHeader.let { if (it.exists) metadataReader.loadIrHeader(library) else null }}}
 
     override fun irDeclaration(index: Long, isLocal: Boolean) = layout.inPlace { metadataReader.loadIrDeclaraton(it, index, isLocal) }