Added shadow singleton value to resolve cycles during initialization

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

@@ -281,6 +281,16 @@ internal val ClassDescriptor.objectInstanceFieldSymbolName: String
         return "kobjref:$fqNameSafe"
     }
 
+internal val ClassDescriptor.objectInstanceShadowFieldSymbolName: String
+    get() {
+        assert (this.isExported())
+        assert (this.kind.isSingleton)
+        assert (!this.isUnit())
+        assert (this.symbol.objectIsShared)
+
+        return "kshadowobjref:$fqNameSafe"
+    }
+
 internal val ClassDescriptor.typeInfoHasVtableAttached: Boolean
     get() = !this.isAbstract() && !this.isExternalObjCClass()
 

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

@@ -63,6 +63,24 @@ internal class CodeGenerator(override val context: Context) : ContextUtils {
         return llvmGlobal
     }
 
+    fun getObjectInstanceShadowStorage(descriptor: ClassDescriptor): LLVMValueRef {
+        assert (!descriptor.isUnit())
+        assert (descriptor.symbol.objectIsShared)
+        val llvmGlobal = if (!isExternal(descriptor)) {
+            context.llvmDeclarations.forSingleton(descriptor).instanceShadowFieldRef!!
+        } else {
+            val llvmType = getLLVMType(descriptor.defaultType)
+            importGlobal(
+                    descriptor.objectInstanceShadowFieldSymbolName,
+                    llvmType,
+                    origin = descriptor.llvmSymbolOrigin,
+                    threadLocal = true
+            )
+        }
+        context.llvm.objects += llvmGlobal
+        return llvmGlobal
+    }
+
     fun typeInfoForAllocation(constructedClass: ClassDescriptor): LLVMValueRef {
         val descriptorForTypeInfo = if (constructedClass.isObjCClass()) {
             context.ir.symbols.objCPointerHolder.owner
@@ -575,28 +593,41 @@ internal class FunctionGenerationContext(val function: LLVMValueRef,
             return codegen.theUnitInstanceRef.llvm
         }
 
+        val args = mutableListOf<LLVMValueRef>()
         val objectPtr = codegen.getObjectInstanceStorage(descriptor)
+        args += objectPtr
         val bbCurrent = currentBlock
-        val bbInit    = basicBlock("label_init", locationInfo)
+        val bbFirstCheck    = basicBlock(if (shared) "label_check_shadow" else "label_init", locationInfo)
         val bbExit    = basicBlock("label_continue", locationInfo)
         val objectVal = loadSlot(objectPtr, false)
-        val condition = icmpUGt(ptrToInt(objectVal, codegen.intPtrType), codegen.immOneIntPtrType)
+        val objectInitialized = icmpUGt(ptrToInt(objectVal, codegen.intPtrType), codegen.immOneIntPtrType)
-        condBr(condition, bbExit, bbInit)
+        condBr(objectInitialized, bbExit, bbFirstCheck)
+
+        positionAtEnd(bbExit)
+        val valuePhi = phi(codegen.getLLVMType(descriptor.defaultType))
+
+        positionAtEnd(bbFirstCheck)
+        if (shared) {
+            val shadowObjectPtr = codegen.getObjectInstanceShadowStorage(descriptor)
+            args += shadowObjectPtr
+            val shadowObjectVal = loadSlot(shadowObjectPtr, false)
+            val shadowNotNull = icmpNe(bitcast(int8TypePtr, shadowObjectVal), kNullInt8Ptr)
+            val bbInit = basicBlock("label_init", locationInfo)
+            condBr(shadowNotNull, bbExit, bbInit)
+            addPhiIncoming(valuePhi, bbFirstCheck to shadowObjectVal)
+            positionAtEnd(bbInit)
+        }
 
-        positionAtEnd(bbInit)
-        val typeInfo = codegen.typeInfoForAllocation(descriptor)
         val defaultConstructor = descriptor.constructors.first { it.valueParameters.size == 0 }
-        val ctor = codegen.llvmFunction(defaultConstructor)
+        args += codegen.typeInfoForAllocation(descriptor)
-        val args = listOf(objectPtr, typeInfo, ctor)
+        args += codegen.llvmFunction(defaultConstructor)
         val initFunction = if (shared) context.llvm.initSharedInstanceFunction else context.llvm.initInstanceFunction
         val newValue = call(initFunction, args, Lifetime.GLOBAL, exceptionHandler)
         val bbInitResult = currentBlock
         br(bbExit)
 
         positionAtEnd(bbExit)
-        val valuePhi = phi(codegen.getLLVMType(descriptor.defaultType))
+        addPhiIncoming(valuePhi, bbCurrent to objectVal, bbInitResult to newValue)
-        addPhiIncoming(valuePhi,
-                bbCurrent to objectVal, bbInitResult to newValue)
 
         return valuePhi
     }

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

@@ -74,7 +74,7 @@ internal class ClassLlvmDeclarations(
         val singletonDeclarations: SingletonLlvmDeclarations?,
         val objCDeclarations: KotlinObjCClassLlvmDeclarations?)
 
-internal class SingletonLlvmDeclarations(val instanceFieldRef: LLVMValueRef)
+internal class SingletonLlvmDeclarations(val instanceFieldRef: LLVMValueRef, val instanceShadowFieldRef: LLVMValueRef?)
 
 internal class KotlinObjCClassLlvmDeclarations(
         val classPointerGlobal: StaticData.Global,
@@ -319,7 +319,20 @@ private class DeclarationsGeneratorVisitor(override val context: Context) :
 
         LLVMSetInitializer(instanceFieldRef, kNullObjHeaderPtr)
 
-        return SingletonLlvmDeclarations(instanceFieldRef)
+        val instanceShadowFieldRef =
+                if (threadLocal) null
+                else {
+                    val shadowSymbolName = if (isExported) {
+                        descriptor.objectInstanceShadowFieldSymbolName
+                    } else {
+                        "kshadowobjref:" + qualifyInternalName(descriptor)
+                    }
+                    addGlobal(shadowSymbolName, getLLVMType(descriptor.defaultType), isExported = isExported, threadLocal = true)
+                }
+
+        instanceShadowFieldRef?.let { LLVMSetInitializer(it, kNullObjHeaderPtr) }
+
+        return SingletonLlvmDeclarations(instanceFieldRef, instanceShadowFieldRef)
     }
 
     private fun createKotlinObjCClassDeclarations(descriptor: ClassDescriptor): KotlinObjCClassLlvmDeclarations {

runtime/src/main/cpp/Memory.cpp

@@ -1104,12 +1104,14 @@ OBJ_GETTER(InitInstance,
 }
 
 OBJ_GETTER(InitSharedInstance,
-    ObjHeader** location, const TypeInfo* type_info, void (*ctor)(ObjHeader*)) {
+    ObjHeader** location, ObjHeader** localLocation, const TypeInfo* type_info, void (*ctor)(ObjHeader*)) {
 #if KONAN_NO_THREADS
   return InitInstance(location, type_info, ctor);
 #else
+  ObjHeader* value = *localLocation;
+  if (value != nullptr) RETURN_OBJ(value);
+
   ObjHeader* initializing = reinterpret_cast<ObjHeader*>(1);
-  ObjHeader* value;
 
   // Spin lock.
   while ((value = __sync_val_compare_and_swap(location, nullptr, initializing)) == initializing);
@@ -1120,19 +1122,22 @@ OBJ_GETTER(InitSharedInstance,
 
   ObjHeader* object = AllocInstance(type_info, OBJ_RESULT);
   MEMORY_LOG("Calling UpdateRef from InitInstance\n")
-  UpdateRef(location, object);
+  UpdateRef(localLocation, object);
-  __sync_synchronize();
 #if KONAN_NO_EXCEPTIONS
   ctor(object);
   // TODO: uncomment as soon as cycles are correctly handled during freezing.
   //if (!object->container()->frozen())
     //ThrowFreezingException();
+  UpdateRef(location, object);
+  __sync_synchronize();
   return object;
 #else
   try {
     ctor(object);
     //if (!object->container()->frozen())
       //ThrowFreezingException();
+    UpdateRef(location, object);
+    __sync_synchronize();
     return object;
   } catch (...) {
     UpdateRef(OBJ_RESULT, nullptr);