Don't emit fields for interop static const vals

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

@@ -65,7 +65,7 @@ internal fun produceOutput(context: Context, phaser: PhaseManager) {
             val abiVersion = context.config.currentAbiVersion
             val target = context.config.target
             val nopack = config.getBoolean(KonanConfigKeys.NOPACK)
-            val manifest = config.get(KonanConfigKeys.MANIFEST_FILE)
+            val manifestProperties = context.config.manifestProperties
 
             val library = buildLibrary(
                 context.config.nativeLibraries, 
@@ -78,7 +78,7 @@ internal fun produceOutput(context: Context, phaser: PhaseManager) {
                 libraryName, 
                 llvmModule,
                 nopack,
-                manifest,
+                manifestProperties,
                 context.dataFlowGraph)
 
             context.library = library

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

@@ -18,6 +18,7 @@ import org.jetbrains.kotlin.konan.file.File
 import org.jetbrains.kotlin.konan.library.KonanLibrary
 import org.jetbrains.kotlin.konan.library.defaultResolver
 import org.jetbrains.kotlin.konan.library.libraryResolver
+import org.jetbrains.kotlin.konan.properties.loadProperties
 import org.jetbrains.kotlin.konan.target.*
 
 class KonanConfig(val project: Project, val configuration: CompilerConfiguration) {
@@ -103,6 +104,12 @@ class KonanConfig(val project: Project, val configuration: CompilerConfiguration
 
     internal val friendModuleFiles: Set<File> =
             configuration.get(KonanConfigKeys.FRIEND_MODULES)?.map { File(it) }?.toSet() ?: emptySet()
+
+    internal val manifestProperties = configuration.get(KonanConfigKeys.MANIFEST_FILE)?.let {
+        File(it).loadProperties()
+    }
+
+    internal val isInteropStubs: Boolean get() = manifestProperties?.getProperty("interop") == "true"
 }
 
 fun CompilerConfiguration.report(priority: CompilerMessageSeverity, message: String) 

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

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.backend.konan.library
 
 import llvm.LLVMModuleRef
 import org.jetbrains.kotlin.konan.library.KonanLibrary
+import java.util.*
 
 const val KLIB_CURRENT_ABI_VERSION = 1
 
@@ -16,7 +17,7 @@ interface KonanLibraryWriter {
     fun addIncludedBinary(library: String)
     fun addKotlinBitcode(llvmModule: LLVMModuleRef)
     fun addLinkDependencies(libraries: List<KonanLibrary>)
-    fun addManifestAddend(path: String)
+    fun addManifestAddend(properties: Properties)
     fun addDataFlowGraph(dataFlowGraph: ByteArray)
     val mainBitcodeFileName: String
     fun commit()

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

@@ -88,8 +88,7 @@ class LibraryWriterImpl(
         }
     }
 
-    override fun addManifestAddend(path: String) {
-        val properties = File(path).loadProperties()
+    override fun addManifestAddend(properties: Properties) {
         manifestProperties.putAll(properties)
     }
 
@@ -117,7 +116,7 @@ internal fun buildLibrary(
         moduleName: String,
         llvmModule: LLVMModuleRef,
         nopack: Boolean,
-        manifest: String?,
+        manifestProperties: Properties?,
         dataFlowGraph: ByteArray?): KonanLibraryWriter {
 
     val library = LibraryWriterImpl(output, moduleName, abiVersion, target, nopack)
@@ -130,7 +129,7 @@ internal fun buildLibrary(
     included.forEach {
         library.addIncludedBinary(it)
     }
-    manifest ?.let { library.addManifestAddend(it) }
+    manifestProperties?.let { library.addManifestAddend(it) }
     library.addLinkDependencies(linkDependencies)
     dataFlowGraph?.let { library.addDataFlowGraph(it) }
 

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

@@ -674,6 +674,39 @@ internal class InteropLoweringPart1(val context: Context) : IrBuildingTransforme
         }
     }
 
+    override fun visitProperty(declaration: IrProperty): IrStatement {
+        val backingField = declaration.backingField
+        return if (declaration.isConst && backingField?.isStatic == true && context.config.isInteropStubs) {
+            // Transform top-level `const val x = 42` to `val x get() = 42`.
+            // Generally this transformation is just an optimization to ensure that interop constants
+            // don't require any storage and/or initialization at program startup.
+            // Also it is useful due to uncertain design of top-level stored properties in Kotlin/Native.
+            val initializer = backingField.initializer!!.expression
+            declaration.backingField = null
+
+            val getter = declaration.getter!!
+            val getterBody = getter.body!! as IrBlockBody
+            getterBody.statements.clear()
+            getterBody.statements += IrReturnImpl(
+                    declaration.startOffset,
+                    declaration.endOffset,
+                    context.irBuiltIns.nothingType,
+                    getter.symbol,
+                    initializer
+            )
+            // Note: in interop stubs const val initializer is either `IrConst` or quite simple expression,
+            // so it is ok to compute it every time.
+
+            assert(declaration.setter == null)
+            assert(!declaration.isVar)
+
+            declaration.transformChildrenVoid()
+            declaration
+        } else {
+            super.visitProperty(declaration)
+        }
+    }
+
     private fun IrBuilderWithScope.callAllocAndInit(
             classPtr: IrExpression,
             initMethodInfo: ObjCMethodInfo,