Avoid requesting selectors in Objective-C interop stubs

Selector references aren't DCEed and thus can cause false positive
API usage report from AppStore online validation.
Generate selectors by compiler instead.

Interop/Runtime/src/native/kotlin/kotlinx/cinterop/ObjectiveCImpl.kt

@@ -125,6 +125,10 @@ annotation class InteropStubs()
 @Retention(AnnotationRetention.SOURCE)
 internal annotation class ObjCMethodImp(val selector: String, val encoding: String)
 
+@PublishedApi
+@TypedIntrinsic(IntrinsicType.OBJC_GET_SELECTOR)
+internal external fun objCGetSelector(selector: String): COpaquePointer
+
 @kotlin.native.internal.ExportForCppRuntime("Kotlin_Interop_getObjCClass")
 private fun getObjCClassByName(name: NativePtr): NativePtr {
     val result = objc_lookUpClass(name)

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/ObjCStubs.kt

@@ -178,6 +178,7 @@ class ObjCMethodStub(private val stubGenerator: StubGenerator,
 
         val kniReceiverParameter = "kniR"
         val kniSuperClassParameter = "kniSC"
+        val kniSelectorParameter = "kniSEL"
 
         val voidPtr = PointerType(VoidType)
 
@@ -199,6 +200,9 @@ class ObjCMethodStub(private val stubGenerator: StubGenerator,
                 TypedKotlinValue(voidPtr,
                         "getReceiverOrSuper($kniReceiverParameter, $kniSuperClassParameter)"))
 
+        kotlinObjCBridgeParameters.add(KotlinParameter(kniSelectorParameter, KotlinTypes.cOpaquePointer))
+        nativeBridgeArguments.add(TypedKotlinValue(voidPtr, kniSelectorParameter))
+
         val kotlinParameterNames = method.getKotlinParameterNames()
 
         method.parameters.forEachIndexed { index, it ->
@@ -224,7 +228,6 @@ class ObjCMethodStub(private val stubGenerator: StubGenerator,
                 returnType,
                 nativeBridgeArguments
         ) { nativeValues ->
-            val selector = "@selector(${method.selector})"
             val messengerParameterTypes = mutableListOf<String>()
             messengerParameterTypes.add("void*")
             messengerParameterTypes.add("SEL")
@@ -239,7 +242,7 @@ class ObjCMethodStub(private val stubGenerator: StubGenerator,
 
             val messenger = "(($messengerType) ${nativeValues.first()})"
 
-            val messengerArguments = listOf(nativeValues[1]) + selector + nativeValues.drop(2)
+            val messengerArguments = nativeValues.drop(1)
 
             "$messenger(${messengerArguments.joinToString()})"
         }

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

@@ -233,6 +233,8 @@ internal class KonanSymbols(context: Context, val symbolTable: SymbolTable, val
     val interopCreateNSStringFromKString =
             symbolTable.referenceSimpleFunction(context.interopBuiltIns.CreateNSStringFromKString)
 
+    val interopObjCGetSelector = interopFunction("objCGetSelector")
+
     val objCExportTrapOnUndeclaredException =
             symbolTable.referenceSimpleFunction(context.builtIns.kotlinNativeInternal.getContributedFunctions(
                     Name.identifier("trapOnUndeclaredException"),

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

@@ -4,6 +4,7 @@ import kotlinx.cinterop.cValuesOf
 import llvm.*
 import org.jetbrains.kotlin.backend.konan.descriptors.TypedIntrinsic
 import org.jetbrains.kotlin.backend.konan.descriptors.isTypedIntrinsic
+import org.jetbrains.kotlin.backend.konan.llvm.objc.genObjCSelector
 import org.jetbrains.kotlin.backend.konan.reportCompilationError
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrConstructor
@@ -51,6 +52,7 @@ internal enum class IntrinsicType {
     OBJC_GET_OBJC_CLASS,
     OBJC_GET_RECEIVER_OR_SUPER,
     OBJC_INIT_BY,
+    OBJC_GET_SELECTOR,
     // Other
     GET_CLASS_TYPE_INFO,
     CREATE_UNINITIALIZED_INSTANCE,
@@ -148,6 +150,10 @@ internal class IntrinsicGenerator(private val environment: IntrinsicGeneratorEnv
                 environment.evaluateCall(constructorDescriptor, args, Lifetime.IRRELEVANT)
                 receiver
             }
+            IntrinsicType.OBJC_GET_SELECTOR -> {
+                val selector = (callSite.getValueArgument(0) as IrConst<*>).value as String
+                environment.functionGenerationContext.genObjCSelector(selector)
+            }
             IntrinsicType.INIT_INSTANCE -> {
                 val callee = callSite as IrCall
                 val initializer = callee.getValueArgument(1) as IrCall
@@ -232,6 +238,7 @@ internal class IntrinsicGenerator(private val environment: IntrinsicGeneratorEnv
                     reportNonLoweredIntrinsic(intrinsicType)
                 IntrinsicType.INIT_INSTANCE,
                 IntrinsicType.OBJC_INIT_BY,
+                IntrinsicType.OBJC_GET_SELECTOR,
                 IntrinsicType.IMMUTABLE_BLOB ->
                     reportSpecialIntrinsic(intrinsicType)
             }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/objc/ObjCCodeGenerator.kt

@@ -14,11 +14,7 @@ internal open class ObjCCodeGenerator(val codegen: CodeGenerator) {
 
     val dataGenerator = codegen.objCDataGenerator!!
 
-    fun FunctionGenerationContext.genSelector(selector: String): LLVMValueRef {
-        val selectorRef = dataGenerator.genSelectorRef(selector)
-        // TODO: clang emits it with `invariant.load` metadata.
-        return load(selectorRef.llvm)
-    }
+    fun FunctionGenerationContext.genSelector(selector: String): LLVMValueRef = genObjCSelector(selector)
 
     fun FunctionGenerationContext.genGetLinkedClass(name: String): LLVMValueRef {
         val classRef = dataGenerator.genClassRef(name)
@@ -43,3 +39,9 @@ internal open class ObjCCodeGenerator(val codegen: CodeGenerator) {
     fun msgSender(functionType: LLVMTypeRef): LLVMValueRef =
             objcMsgSend.bitcast(pointerType(functionType)).llvm
 }
+
+internal fun FunctionGenerationContext.genObjCSelector(selector: String): LLVMValueRef {
+    val selectorRef = codegen.objCDataGenerator!!.genSelectorRef(selector)
+    // TODO: clang emits it with `invariant.load` metadata.
+    return load(selectorRef.llvm)
+}

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

@@ -587,10 +587,13 @@ internal class InteropLoweringPart1(val context: Context) : IrBuildingTransforme
         return irCall(bridge, symbolTable.translateErased(info.bridge.returnType!!)).apply {
             putValueArgument(0, superClass)
             putValueArgument(1, receiver)
+            putValueArgument(2, irCall(symbols.interopObjCGetSelector.owner).apply {
+                putValueArgument(0, irString(info.selector))
+            })
 
-            assert(arguments.size + 2 == info.bridge.valueParameters.size)
+            assert(arguments.size + 3 == info.bridge.valueParameters.size)
             arguments.forEachIndexed { index, argument ->
-                putValueArgument(index + 2, argument)
+                putValueArgument(index + 3, argument)
             }
         }
     }

runtime/src/main/kotlin/kotlin/native/internal/IntrinsicType.kt

@@ -42,6 +42,7 @@ class IntrinsicType {
         const val OBJC_GET_OBJC_CLASS           = "OBJC_GET_OBJC_CLASS"
         const val OBJC_GET_RECEIVER_OR_SUPER    = "OBJC_GET_RECEIVER_OR_SUPER"
         const val OBJC_INIT_BY                  = "OBJC_INIT_BY"
+        const val OBJC_GET_SELECTOR             = "OBJC_GET_SELECTOR"
 
         // Other
         const val GET_CLASS_TYPE_INFO           = "GET_CLASS_TYPE_INFO"