[NativeAOT] Objective-C Marshal: object tracker support

src/coreclr/nativeaot/Bootstrap/main.cpp

@@ -112,6 +112,11 @@ extern "C" void OnFirstChanceException();
 extern "C" void OnUnhandledException();
 extern "C" void IDynamicCastableIsInterfaceImplemented();
 extern "C" void IDynamicCastableGetInterfaceImplementation();
+#ifdef FEATURE_OBJCMARSHAL
+extern "C" void ObjectiveCMarshalTryGetTaggedMemory();
+extern "C" void ObjectiveCMarshalGetIsTrackedReferenceCallback();
+extern "C" void ObjectiveCMarshalGetOnEnteredFinalizerQueueCallback();
+#endif
 
 typedef void(*pfn)();
 
@@ -126,6 +131,15 @@ static const pfn c_classlibFunctions[] = {
     &OnUnhandledException,
     &IDynamicCastableIsInterfaceImplemented,
     &IDynamicCastableGetInterfaceImplementation,
+#ifdef FEATURE_OBJCMARSHAL
+    &ObjectiveCMarshalTryGetTaggedMemory,
+    &ObjectiveCMarshalGetIsTrackedReferenceCallback,
+    &ObjectiveCMarshalGetOnEnteredFinalizerQueueCallback,
+#else
+    nullptr,
+    nullptr,
+    nullptr,
+#endif
 };
 
 #ifndef _countof

src/coreclr/nativeaot/CMakeLists.txt

@@ -34,6 +34,7 @@ if(CLR_CMAKE_HOST_UNIX)
 
   if(CLR_CMAKE_TARGET_OSX)
     add_definitions(-D_XOPEN_SOURCE)
+    add_definitions(-DFEATURE_OBJCMARSHAL)
   endif(CLR_CMAKE_TARGET_OSX)
 
   if(CLR_CMAKE_TARGET_ARCH_AMD64 OR CLR_CMAKE_TARGET_ARCH_I386)

src/coreclr/nativeaot/Common/src/Internal/Runtime/MethodTable.cs

@@ -791,6 +791,14 @@ internal bool IsHFA
             }
         }
 
+        internal bool IsTrackedReferenceWithFinalizer
+        {
+            get
+            {
+                return (ExtendedFlags & (ushort)EETypeFlagsEx.IsTrackedReferenceWithFinalizerFlag) != 0;
+            }
+        }
+
         internal uint ValueTypeFieldPadding
         {
             get

src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/InternalCalls.cs

@@ -44,6 +44,9 @@ internal enum ClassLibFunctionId
         OnUnhandledException = 7,
         IDynamicCastableIsInterfaceImplemented = 8,
         IDynamicCastableGetInterfaceImplementation = 9,
+        ObjectiveCMarshalTryGetTaggedMemory = 10,
+        ObjectiveCMarshalGetIsTrackedReferenceCallback = 11,
+        ObjectiveCMarshalGetOnEnteredFinalizerQueueCallback = 12,
     }
 
     internal static class InternalCalls

src/coreclr/nativeaot/Runtime/CMakeLists.txt

@@ -170,6 +170,12 @@ else()
   set(ASM_SUFFIX S)
 endif()
 
+if (CLR_CMAKE_TARGET_OSX)
+  list(APPEND COMMON_RUNTIME_SOURCES
+    interoplibinterface_objc.cpp
+  )
+endif (CLR_CMAKE_TARGET_OSX)
+
 if (CLR_CMAKE_TARGET_ARCH_AMD64 AND CLR_CMAKE_TARGET_WIN32)
   list(APPEND COMMON_RUNTIME_SOURCES
     ${GC_DIR}/vxsort/isa_detection.cpp

src/coreclr/nativeaot/Runtime/Crst.h

@@ -18,6 +18,7 @@ enum CrstType
     CrstInterfaceDispatchGlobalLists,
     CrstStressLog,
     CrstRestrictedCallouts,
+    CrstObjectiveCMarshalCallouts,
     CrstGcStressControl,
     CrstSuspendEE,
     CrstCastCache,

src/coreclr/nativeaot/Runtime/GCHelpers.cpp

@@ -18,6 +18,7 @@
 #include "varint.h"
 #include "regdisplay.h"
 #include "StackFrameIterator.h"
+#include "interoplibinterface.h"
 
 #include "thread.h"
 #include "RWLock.h"
@@ -132,6 +133,13 @@ COOP_PINVOKE_HELPER(void, RhUnregisterGcCallout, (GcRestrictedCalloutKind eKind,
     RestrictedCallouts::UnregisterGcCallout(eKind, pCallout);
 }
 
+#ifdef FEATURE_OBJCMARSHAL
+COOP_PINVOKE_HELPER(FC_BOOL_RET, RhRegisterObjectiveCMarshalBeginEndCallback, (void * pCallback))
+{
+    FC_RETURN_BOOL(ObjCMarshalNative::RegisterBeginEndCallback(pCallback));
+}
+#endif
+
 COOP_PINVOKE_HELPER(int32_t, RhGetLohCompactionMode, ())
 {
     return GCHeapUtilities::GetGCHeap()->GetLOHCompactionMode();

src/coreclr/nativeaot/Runtime/ICodeManager.h

@@ -154,6 +154,9 @@ enum class ClasslibFunctionId
     OnUnhandledException = 7,
     IDynamicCastableIsInterfaceImplemented = 8,
     IDynamicCastableGetInterfaceImplementation = 9,
+    ObjectiveCMarshalTryGetTaggedMemory = 10,
+    ObjectiveCMarshalGetIsTrackedReferenceCallback = 11,
+    ObjectiveCMarshalGetOnEnteredFinalizerQueueCallback = 12,
 };
 
 enum class AssociatedDataFlags : unsigned char

src/coreclr/nativeaot/Runtime/gcrhenv.cpp

@@ -45,6 +45,7 @@
 #include "daccess.h"
 
 #include "GCMemoryHelpers.h"
+#include "interoplibinterface.h"
 
 #include "holder.h"
 #include "volatile.h"
@@ -682,13 +683,25 @@ void GCToEEInterface::GcStartWork(int condemned, int /*max_gen*/)
 
 void GCToEEInterface::BeforeGcScanRoots(int condemned, bool is_bgc, bool is_concurrent)
 {
+#ifdef FEATURE_OBJCMARSHAL
+    if (!is_concurrent)
+    {
+        ObjCMarshalNative::BeforeRefCountedHandleCallbacks();
+    }
+#endif
 }
 
 // EE can perform post stack scanning action, while the user threads are still suspended
-void GCToEEInterface::AfterGcScanRoots(int condemned, int /*max_gen*/, ScanContext* /*sc*/)
+void GCToEEInterface::AfterGcScanRoots(int condemned, int /*max_gen*/, ScanContext* sc)
 {
     // Invoke any registered callouts for the end of the mark phase.
     RestrictedCallouts::InvokeGcCallouts(GCRC_AfterMarkPhase, condemned);
+#ifdef FEATURE_OBJCMARSHAL
+    if (!sc->concurrent)
+    {
+        ObjCMarshalNative::AfterRefCountedHandleCallbacks();
+    }
+#endif
 }
 
 void GCToEEInterface::GcDone(int condemned)
@@ -699,6 +712,11 @@ void GCToEEInterface::GcDone(int condemned)
 
 bool GCToEEInterface::RefCountedHandleCallbacks(Object * pObject)
 {
+#ifdef FEATURE_OBJCMARSHAL
+    bool isReferenced = false;
+    if (ObjCMarshalNative::IsTrackedReference(pObject, &isReferenced))
+        return isReferenced;
+#endif // FEATURE_OBJCMARSHAL
     return RestrictedCallouts::InvokeRefCountedHandleCallbacks(pObject);
 }
 
@@ -1153,6 +1171,14 @@ void GCToEEInterface::HandleFatalError(unsigned int exitCode)
 
 bool GCToEEInterface::EagerFinalized(Object* obj)
 {
+#ifdef FEATURE_OBJCMARSHAL
+    if (obj->GetGCSafeMethodTable()->IsTrackedReferenceWithFinalizer())
+    {
+        ObjCMarshalNative::OnEnteredFinalizerQueue(obj);
+        return false;
+    }
+#endif
+
     if (!obj->GetGCSafeMethodTable()->HasEagerFinalizer())
         return false;
 

src/coreclr/nativeaot/Runtime/inc/MethodTable.h

@@ -194,6 +194,7 @@ class MethodTable
     {
         HasEagerFinalizerFlag = 0x0001,
         HasCriticalFinalizerFlag = 0x0002,
+        IsTrackedReferenceWithFinalizerFlag = 0x0004,
     };
 
 public:
@@ -269,6 +270,11 @@ class MethodTable
         return (m_uFlags & HasCriticalFinalizerFlag) && !HasComponentSize();
     }
 
+    bool IsTrackedReferenceWithFinalizer()
+    {
+        return (m_uFlags & IsTrackedReferenceWithFinalizerFlag) && !HasComponentSize();
+    }
+
     bool  HasComponentSize()
     {
         static_assert(HasComponentSizeFlag == (MethodTable::Flags)(1 << 31), "we assume that HasComponentSizeFlag matches the sign bit");

src/coreclr/nativeaot/Runtime/interoplibinterface.h

@@ -0,0 +1,24 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#ifdef FEATURE_OBJCMARSHAL
+
+class ObjCMarshalNative
+{
+public:
+    using TryGetCallback = void*(REDHAWK_CALLCONV *)(void);
+    using TryGetTaggedMemoryCallback = CLR_BOOL(REDHAWK_CALLCONV *)(_In_ Object *, _Out_ void **);
+    using BeginEndCallback = void(REDHAWK_CALLCONV *)(void);
+    using IsReferencedCallback = int(REDHAWK_CALLCONV *)(_In_ void*);
+    using EnteredFinalizationCallback = void(REDHAWK_CALLCONV *)(_In_ void*);
+
+public: // Instance inspection
+    static bool IsTrackedReference(_In_ Object * pObject, _Out_ bool* isReferenced);
+public: // GC interaction
+    static bool RegisterBeginEndCallback(void * callback);
+    static void BeforeRefCountedHandleCallbacks();
+    static void AfterRefCountedHandleCallbacks();
+    static void OnEnteredFinalizerQueue(_In_ Object * object);
+};
+
+#endif // FEATURE_OBJCMARSHAL

src/coreclr/nativeaot/Runtime/interoplibinterface_objc.cpp

@@ -0,0 +1,178 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#include "common.h"
+#include "CommonTypes.h"
+#include "CommonMacros.h"
+#include "daccess.h"
+#include "PalRedhawkCommon.h"
+#include "PalRedhawk.h"
+#include "rhassert.h"
+#include "slist.h"
+#include "holder.h"
+#include "gcrhinterface.h"
+#include "shash.h"
+#include "RWLock.h"
+#include "rhbinder.h"
+#include "Crst.h"
+#include "RuntimeInstance.h"
+#include "TypeManager.h"
+#include "MethodTable.h"
+#include "ObjectLayout.h"
+#include "event.h"
+#include "varint.h"
+#include "regdisplay.h"
+#include "StackFrameIterator.h"
+#include "thread.h"
+#include "threadstore.h"
+#include "threadstore.inl"
+
+#include "interoplibinterface.h"
+
+#include "MethodTable.inl"
+
+#ifdef FEATURE_OBJCMARSHAL
+
+namespace
+{
+    // TODO: Support registering multiple begin/end callbacks.
+    // NativeAOT support the concept of multiple managed "worlds",
+    // each with their own object heirarchy. Each of these worlds
+    // could potentially have its own set of callbacks.
+    // However this Objective-C Marshal API was not designed with such a
+    // possibility in mind.
+    ObjCMarshalNative::BeginEndCallback s_pBeginEndCallback = nullptr;
+
+    struct DisableTriggerGcWhileCallingManagedCode
+    {
+        Thread * m_pThread;
+        bool m_fGcStressWasSuppressed;
+
+        DisableTriggerGcWhileCallingManagedCode()
+        {
+            // It is illegal for any of the callouts to trigger a GC.
+            m_pThread = ThreadStore::GetCurrentThread();
+            m_pThread->SetDoNotTriggerGc();
+
+            // Due to the above we have better suppress GC stress.
+            m_fGcStressWasSuppressed = m_pThread->IsSuppressGcStressSet();
+            if (!m_fGcStressWasSuppressed)
+                m_pThread->SetSuppressGcStress();
+        }
+
+        ~DisableTriggerGcWhileCallingManagedCode()
+        {
+            // Revert GC stress mode if we changed it.
+            if (!m_fGcStressWasSuppressed)
+                m_pThread->ClearSuppressGcStress();
+
+            m_pThread->ClearDoNotTriggerGc();
+        }
+    };
+
+    bool TryGetTaggedMemory(_In_ Object * obj, _Out_ void ** tagged)
+    {
+        void* fn = obj->get_EEType()
+                       ->GetTypeManagerPtr()
+                       ->AsTypeManager()
+                       ->GetClasslibFunction(ClasslibFunctionId::ObjectiveCMarshalTryGetTaggedMemory);
+
+        ASSERT(fn != nullptr);
+
+        auto pTryGetTaggedMemoryCallback = reinterpret_cast<ObjCMarshalNative::TryGetTaggedMemoryCallback>(fn);
+
+        DisableTriggerGcWhileCallingManagedCode disabler{};
+
+        bool result = pTryGetTaggedMemoryCallback(obj, tagged);
+
+        return result;
+    }
+
+    // Calls a managed classlib function to potentially get an unmanaged callback.
+    // Not for use with ObjectiveCMarshalTryGetTaggedMemory.
+    void * GetCallbackViaClasslibCallback(_In_ Object * object, _In_ ClasslibFunctionId id)
+    {
+        void* fn = object->get_EEType()
+                        ->GetTypeManagerPtr()
+                        ->AsTypeManager()
+                        ->GetClasslibFunction(id);
+
+        ASSERT(fn != nullptr);
+
+        DisableTriggerGcWhileCallingManagedCode disabler{};
+
+        fn = ((ObjCMarshalNative::TryGetCallback)fn)();
+
+        ASSERT(fn != nullptr);
+
+        return fn;
+    }
+}
+
+bool ObjCMarshalNative::RegisterBeginEndCallback(void * callback)
+{
+    ASSERT(callback != nullptr);
+
+    // We must be in Cooperative mode since we are setting callbacks that
+    // will be used during a GC and we want to ensure a GC isn't occurring
+    // while they are being set.
+    ASSERT(ThreadStore::GetCurrentThread()->IsCurrentThreadInCooperativeMode());
+
+    return PalInterlockedCompareExchangePointer(&s_pBeginEndCallback, callback, nullptr) == nullptr;
+}
+
+bool ObjCMarshalNative::IsTrackedReference(_In_ Object * object, _Out_ bool* isReferenced)
+{
+    *isReferenced = false;
+
+    if (!object->GetGCSafeMethodTable()->IsTrackedReferenceWithFinalizer())
+        return false;
+
+    auto pIsReferencedCallbackCallback = (ObjCMarshalNative::IsReferencedCallback)GetCallbackViaClasslibCallback(
+        object, ClasslibFunctionId::ObjectiveCMarshalGetIsTrackedReferenceCallback);
+
+    void* taggedMemory;
+    if (!TryGetTaggedMemory(object, &taggedMemory))
+    {
+        // It should not be possible to create a ref-counted handle
+        // without setting up the tagged memory first.
+        ASSERT(false);
+        return false;
+    }
+
+    int result = pIsReferencedCallbackCallback(taggedMemory);
+
+    *isReferenced = (result != 0);
+    return true;
+}
+
+void ObjCMarshalNative::BeforeRefCountedHandleCallbacks()
+{
+    if (s_pBeginEndCallback != nullptr)
+        s_pBeginEndCallback();
+}
+
+void ObjCMarshalNative::AfterRefCountedHandleCallbacks()
+{
+    if (s_pBeginEndCallback != nullptr)
+        s_pBeginEndCallback();
+}
+
+void ObjCMarshalNative::OnEnteredFinalizerQueue(_In_ Object * object)
+{
+    auto pOnEnteredFinalizerQueueCallback = (ObjCMarshalNative::EnteredFinalizationCallback)GetCallbackViaClasslibCallback(
+        object, ClasslibFunctionId::ObjectiveCMarshalGetOnEnteredFinalizerQueueCallback);
+
+    void* taggedMemory;
+    if (!TryGetTaggedMemory(object, &taggedMemory))
+    {
+        // Its possible to create an object that supports reference tracking
+        // without ever creating a ref-counted handle for it. In this case,
+        // there will be no tagged memory.
+        return;
+    }
+
+    pOnEnteredFinalizerQueueCallback(taggedMemory);
+}
+
+#endif // FEATURE_OBJCMARSHAL