Fix iOS ARM32 ABI support in Objective-C interop

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

@@ -148,7 +148,7 @@ private fun allocObjCObject(clazz: NativePtr): NativePtr {
 private external fun <T : ObjCObject> getObjCClass(): NativePtr
 
 @konan.internal.Intrinsic external fun getMessenger(superClass: NativePtr): COpaquePointer?
-@konan.internal.Intrinsic external fun getMessengerLU(superClass: NativePtr): COpaquePointer?
+@konan.internal.Intrinsic external fun getMessengerStret(superClass: NativePtr): COpaquePointer?
 
 internal class ObjCWeakReferenceImpl : konan.ref.WeakReferenceImpl() {
     @SymbolName("Konan_ObjCInterop_getWeakReference")

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

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.native.interop.gen
 
+import org.jetbrains.kotlin.konan.target.KonanTarget
 import org.jetbrains.kotlin.native.interop.gen.jvm.StubGenerator
 import org.jetbrains.kotlin.native.interop.indexer.*
 
@@ -155,7 +156,8 @@ class ObjCMethodStub(private val stubGenerator: StubGenerator,
 
         val returnType = method.getReturnType(container.classOrProtocol)
 
-        val messengerGetter = if (returnType.isLargeOrUnaligned()) "getMessengerLU" else "getMessenger"
+        val messengerGetter =
+                if (returnType.isStret(stubGenerator.configuration.target)) "getMessengerStret" else "getMessenger"
 
         kotlinObjCBridgeParameters.add(KotlinParameter(kniSuperClassParameter, KotlinTypes.nativePtr))
         nativeBridgeArguments.add(TypedKotlinValue(voidPtr, "$messengerGetter($kniSuperClassParameter)"))
@@ -277,14 +279,52 @@ private val ObjCContainer.classOrProtocol: ObjCClassOrProtocol
         is ObjCCategory -> this.clazz
     }
 
-private fun Type.isLargeOrUnaligned(): Boolean {
+/**
+ * objc_msgSend*_stret functions must be used when return value is returned through memory
+ * pointed by implicit argument, which is passed on the register that would otherwise be used for receiver.
+ *
+ * The entire implementation is just the real ABI approximation which is enough for practical cases.
+ */
+private fun Type.isStret(target: KonanTarget): Boolean {
     val unwrappedType = this.unwrapTypedefs()
-    return when (unwrappedType) {
-        is RecordType -> unwrappedType.decl.def!!.size > 16 || this.hasUnalignedMembers()
-        else -> false
+    return when (target) {
+        KonanTarget.IOS_ARM64 ->
+            false // On aarch64 stret is never the case, since an implicit argument gets passed on x8.
+
+        KonanTarget.IOS_X64, KonanTarget.MACOS_X64 -> when (unwrappedType) {
+            is RecordType -> unwrappedType.decl.def!!.size > 16 || this.hasUnalignedMembers()
+            else -> false
+        }
+        KonanTarget.IOS_ARM32 -> {
+            when (unwrappedType) {
+                is RecordType -> !this.isIntegerLikeType()
+                else -> false
+            }
+        }
+
+        else -> error(target)
     }
 }
 
+private fun Type.isIntegerLikeType(): Boolean = when (this) {
+    is RecordType -> {
+        val def = this.decl.def
+        if (def == null) {
+            false
+        } else {
+            def.size <= 4 &&
+                    def.bitFields.all { it.type.isIntegerLikeType() } &&
+                    def.fields.all { it.offset == 0L && it.type.isIntegerLikeType() }
+        }
+    }
+    is ObjCPointer, is PointerType, CharType, BoolType -> true
+    is IntegerType -> this.size <= 4
+    is Typedef -> this.def.aliased.isIntegerLikeType()
+    is EnumType -> this.def.baseType.isIntegerLikeType()
+
+    else -> false
+}
+
 private fun Type.hasUnalignedMembers(): Boolean = when (this) {
     is Typedef -> this.def.aliased.hasUnalignedMembers()
     is RecordType -> this.decl.def!!.let { def ->

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

@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.native.interop.gen.jvm
 
+import org.jetbrains.kotlin.konan.target.KonanTarget
 import org.jetbrains.kotlin.native.interop.indexer.NativeLibrary
 
 /**
@@ -29,5 +30,6 @@ class InteropConfiguration(
         val nonStrictEnums: Set<String>,
         val noStringConversion: Set<String>,
         val exportForwardDeclarations: List<String>,
-        val disableDesignatedInitializerChecks: Boolean
+        val disableDesignatedInitializerChecks: Boolean,
+        val target: KonanTarget
 )

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

@@ -30,7 +30,7 @@ class ToolConfig(userProvidedTargetName: String?, flavor: KotlinPlatform) {
     private val platformManager = PlatformManager(distribution)
     private val targetManager = platformManager.targetManager(userProvidedTargetName)
     private val host = HostManager.host
-    private val target = targetManager.target
+    val target = targetManager.target
 
     private val platform = platformManager.platform(target)
 

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

@@ -277,7 +277,8 @@ private fun processCLib(args: Array<String>): Array<String>? {
             nonStrictEnums = def.config.nonStrictEnums.toSet(),
             noStringConversion = def.config.noStringConversion.toSet(),
             exportForwardDeclarations = def.config.exportForwardDeclarations,
-            disableDesignatedInitializerChecks = def.config.disableDesignatedInitializerChecks
+            disableDesignatedInitializerChecks = def.config.disableDesignatedInitializerChecks,
+            target = tool.target
     )
 
     val nativeIndex = buildNativeIndex(library)

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

@@ -173,7 +173,7 @@ internal class InteropBuiltIns(builtIns: KonanBuiltIns) {
     val getObjCReceiverOrSuper = packageScope.getContributedFunctions("getReceiverOrSuper").single()
 
     val getObjCMessenger = packageScope.getContributedFunctions("getMessenger").single()
-    val getObjCMessengerLU = packageScope.getContributedFunctions("getMessengerLU").single()
+    val getObjCMessengerStret = packageScope.getContributedFunctions("getMessengerStret").single()
 
     val interpretObjCPointerOrNull = packageScope.getContributedFunctions("interpretObjCPointerOrNull").single()
     val interpretObjCPointer = packageScope.getContributedFunctions("interpretObjCPointer").single()

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

@@ -42,7 +42,6 @@ import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
 import org.jetbrains.kotlin.konan.target.CompilerOutputKind
-import org.jetbrains.kotlin.konan.target.KonanTarget
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameUnsafe
 
 val IrClassSymbol.objectIsShared get() = owner.origin == DECLARATION_ORIGIN_ENUM
@@ -2165,10 +2164,10 @@ internal class CodeGeneratorVisitor(val context: Context, val lifetimes: Map<IrE
             }
 
             interop.getObjCMessenger -> {
-                genGetObjCMessenger(args, isLU = false)
+                genGetObjCMessenger(args, isStret = false)
             }
-            interop.getObjCMessengerLU -> {
-                genGetObjCMessenger(args, isLU = true)
+            interop.getObjCMessengerStret -> {
+                genGetObjCMessenger(args, isStret = true)
             }
 
             interop.readBits -> genReadBits(args)
@@ -2327,25 +2326,9 @@ internal class CodeGeneratorVisitor(val context: Context, val lifetimes: Map<IrE
         return call(protocolGetter, emptyList())
     }
 
-    private fun genGetObjCMessenger(args: List<LLVMValueRef>, isLU: Boolean): LLVMValueRef {
+    private fun genGetObjCMessenger(args: List<LLVMValueRef>, isStret: Boolean): LLVMValueRef {
         val gen = functionGenerationContext
 
-        // 'LU' means "large or unaligned".
-
-        // objc_msgSend*_stret functions must be used when return value is returned through memory
-        // pointed by implicit argument, which is passed on the register that would otherwise be used for receiver.
-        // On aarch64 it is never the case, since such implicit argument gets passed on x8.
-        // On x86_64 it is the case if the return value takes more than 16 bytes or is the structure with
-        // unaligned fields (there are some complicated exceptions currently ignored). The latter condition
-        // is "encoded" by stub generator by emitting either `getMessenger` or `getMessengerLU` intrinsic call.
-        val isStret = when (context.config.target) {
-            KonanTarget.MACOS_X64, KonanTarget.IOS_X64 -> isLU // x86_64
-            KonanTarget.IOS_ARM64 -> false // aarch64
-            // TODO: what is the correct value?
-            KonanTarget.IOS_ARM32 -> false // armv7
-            else -> TODO()
-        }
-
         val messengerNameSuffix = if (isStret) "_stret" else ""
 
         val functionType = functionType(int8TypePtr, true, int8TypePtr, int8TypePtr)