Switch CoreCLR WeakReference to unified managed implementation

src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj

@@ -133,6 +133,7 @@
     <Compile Include="$(BclSourcesRoot)\System\Collections\Generic\Comparer.CoreCLR.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Collections\Generic\ComparerHelpers.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Collections\Generic\EqualityComparer.CoreCLR.cs" />
+    <Compile Include="$(BclSourcesRoot)\System\ComAwareWeakReference.CoreCLR.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Currency.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Delegate.CoreCLR.cs" />
     <Compile Include="$(BclSourcesRoot)\System\Diagnostics\Debugger.cs" />
@@ -244,8 +245,6 @@
     <Compile Include="$(BclSourcesRoot)\System\TypeLoadException.CoreCLR.cs" />
     <Compile Include="$(BclSourcesRoot)\System\TypeNameParser.cs" />
     <Compile Include="$(BclSourcesRoot)\System\ValueType.cs" />
-    <Compile Include="$(BclSourcesRoot)\System\WeakReference.CoreCLR.cs" />
-    <Compile Include="$(BclSourcesRoot)\System\WeakReference.T.CoreCLR.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(FeatureComWrappers)' == 'true'">
     <Compile Include="$(BclSourcesRoot)\System\Runtime\InteropServices\ComWrappers.cs" />

src/coreclr/System.Private.CoreLib/src/System/ComAwareWeakReference.CoreCLR.cs

@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+#if FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
+namespace System
+{
+    internal sealed partial class ComAwareWeakReference
+    {
+        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "ComWeakRefToObject")]
+        private static partial void ComWeakRefToObject(IntPtr pComWeakRef, long wrapperId, ObjectHandleOnStack retRcw);
+
+        internal static object? ComWeakRefToObject(IntPtr pComWeakRef, long wrapperId)
+        {
+            object? retRcw = null;
+            ComWeakRefToObject(pComWeakRef, wrapperId, ObjectHandleOnStack.Create(ref retRcw));
+            return retRcw;
+        }
+
+        [MethodImpl(MethodImplOptions.InternalCall)]
+        internal static extern IntPtr ObjectToComWeakRef(object target, out long wrapperId);
+    }
+}
+#endif

src/coreclr/System.Private.CoreLib/src/System/GC.CoreCLR.cs

@@ -305,7 +305,7 @@ public static void KeepAlive(object? obj)
         //
         public static int GetGeneration(WeakReference wo)
         {
-            int result = GetGenerationWR(wo.m_handle);
+            int result = GetGenerationWR(wo.WeakHandle);
             KeepAlive(wo);
             return result;
         }

src/coreclr/System.Private.CoreLib/src/System/Runtime/InteropServices/GCHandle.CoreCLR.cs

@@ -8,7 +8,7 @@ namespace System.Runtime.InteropServices
     public partial struct GCHandle
     {
         [MethodImpl(MethodImplOptions.InternalCall)]
-        private static extern IntPtr InternalAlloc(object? value, GCHandleType type);
+        internal static extern IntPtr InternalAlloc(object? value, GCHandleType type);
 
         [MethodImpl(MethodImplOptions.InternalCall)]
         internal static extern void InternalFree(IntPtr handle);

src/coreclr/debug/daccess/daccess.cpp

@@ -7858,10 +7858,6 @@ void CALLBACK DacHandleWalker::EnumCallbackSOS(PTR_UNCHECKED_OBJECTREF handle, u
     data.Type = param->Type;
     if (param->Type == HNDTYPE_DEPENDENT)
         data.Secondary = GetDependentHandleSecondary(handle.GetAddr()).GetAddr();
-#ifdef FEATURE_COMINTEROP
-    else if (param->Type == HNDTYPE_WEAK_NATIVE_COM)
-        data.Secondary = HndGetHandleExtraInfo(handle.GetAddr());
-#endif // FEATURE_COMINTEROP
     else
         data.Secondary = 0;
     data.AppDomain = param->AppDomain;

src/coreclr/debug/daccess/dacdbiimpl.cpp

@@ -7601,10 +7601,6 @@ UINT32 DacRefWalker::GetHandleWalkerMask()
     if ((mHandleMask & CorHandleWeakRefCount) || (mHandleMask & CorHandleStrongRefCount))
         result |= (1 << HNDTYPE_REFCOUNTED);
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-    if (mHandleMask & CorHandleWeakNativeCom)
-        result |= (1 << HNDTYPE_WEAK_NATIVE_COM);
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
 
     if (mHandleMask & CorHandleStrongDependent)
         result |= (1 << HNDTYPE_DEPENDENT);
@@ -7778,11 +7774,6 @@ void CALLBACK DacHandleWalker::EnumCallbackDac(PTR_UNCHECKED_OBJECTREF handle, u
             data.i64ExtraData = refCnt;
             break;
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-        case HNDTYPE_WEAK_NATIVE_COM:
-            data.dwType = (DWORD)CorHandleWeakNativeCom;
-            break;
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
 
         case HNDTYPE_DEPENDENT:
             data.dwType = (DWORD)CorHandleStrongDependent;

src/coreclr/debug/daccess/request.cpp

@@ -3210,9 +3210,6 @@ HRESULT ClrDataAccess::GetHandleEnum(ISOSHandleEnum **ppHandleEnum)
 #if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS) || defined(FEATURE_OBJCMARSHAL)
                             HNDTYPE_REFCOUNTED,
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-                            HNDTYPE_WEAK_NATIVE_COM
-#endif // FEATURE_COMINTEROP
                             };
 
     return GetHandleEnumForTypes(types, ARRAY_SIZE(types), ppHandleEnum);
@@ -3251,9 +3248,6 @@ HRESULT ClrDataAccess::GetHandleEnumForGC(unsigned int gen, ISOSHandleEnum **ppH
 #if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS) || defined(FEATURE_OBJCMARSHAL)
                             HNDTYPE_REFCOUNTED,
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-                            HNDTYPE_WEAK_NATIVE_COM
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
                             };
 
     DacHandleWalker *walker = new DacHandleWalker();

src/coreclr/gc/gchandletable.cpp

@@ -167,7 +167,7 @@ Object* GCHandleManager::InterlockedCompareExchangeObjectInHandle(OBJECTHANDLE h
 HandleType GCHandleManager::HandleFetchType(OBJECTHANDLE handle)
 {
     uint32_t type = ::HandleFetchType(handle);
-    assert(type >= HNDTYPE_WEAK_SHORT && type <= HNDTYPE_WEAK_NATIVE_COM);
+    assert(type >= HNDTYPE_WEAK_SHORT && type <= HNDTYPE_SIZEDREF);
     return static_cast<HandleType>(type);
 }
 

src/coreclr/gc/gcinterface.h

@@ -453,20 +453,6 @@ typedef enum
      *
      */
     HNDTYPE_SIZEDREF     = 8,
-
-    /*
-     * NATIVE WEAK HANDLES
-     *
-     * Native weak reference handles hold two different types of weak handles to any
-     * RCW with an underlying COM object that implements IWeakReferenceSource.  The
-     * object reference itself is a short weak handle to the RCW.  In addition an
-     * IWeakReference* to the underlying COM object is stored, allowing the handle
-     * to create a new RCW if the existing RCW is collected.  This ensures that any
-     * code holding onto a native weak reference can always access an RCW to the
-     * underlying COM object as long as it has not been released by all of its strong
-     * references.
-     */
-    HNDTYPE_WEAK_NATIVE_COM   = 9
 } HandleType;
 
 typedef enum

src/coreclr/gc/handletable.cpp

@@ -407,13 +407,6 @@ void HndDestroyHandleOfUnknownType(HHANDLETABLE hTable, OBJECTHANDLE handle)
     // sanity check handle we are being asked to free
     _ASSERTE(handle);
 
-#ifdef FEATURE_COMINTEROP
-    // If we're being asked to destroy a native COM weak handle, that will cause a leak
-    // of the IWeakReference* that it holds in its extra data. Instead of using this
-    // API use DestroyNativeComWeakHandle instead.
-    _ASSERTE(HandleFetchType(handle) != HNDTYPE_WEAK_NATIVE_COM);
-#endif // FEATURE_COMINTEROP
-
     // fetch the type and then free normally
     HndDestroyHandle(hTable, HandleFetchType(handle), handle);
 }

src/coreclr/gc/objecthandle.cpp

@@ -424,9 +424,6 @@ void CALLBACK ScanPointerForProfilerAndETW(_UNCHECKED_OBJECTREF *pObjRef, uintpt
         break;
     case    HNDTYPE_WEAK_SHORT:
     case    HNDTYPE_WEAK_LONG:
-#ifdef FEATURE_COMINTEROP
-    case    HNDTYPE_WEAK_NATIVE_COM:
-#endif // FEATURE_COMINTEROP
         rootFlags |= kEtwGCRootFlagsWeakRef;
         break;
 
@@ -519,7 +516,6 @@ static const uint32_t s_rgTypeFlags[] =
     HNDF_EXTRAINFO, // HNDTYPE_DEPENDENT
     HNDF_NORMAL,    // HNDTYPE_ASYNCPINNED
     HNDF_EXTRAINFO, // HNDTYPE_SIZEDREF
-    HNDF_EXTRAINFO, // HNDTYPE_WEAK_NATIVE_COM
 };
 
 int getNumberOfSlots()
@@ -1383,14 +1379,7 @@ void Ref_CheckAlive(uint32_t condemned, uint32_t maxgen, uintptr_t lp1)
 
     LOG((LF_GC, LL_INFO10000, "Checking liveness of referents of short-weak handles in generation %u\n", condemned));
 
-    // perform a multi-type scan that checks for unreachable objects
-    uint32_t types[] =
-    {
-        HNDTYPE_WEAK_SHORT
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-        , HNDTYPE_WEAK_NATIVE_COM
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
-    };
+    uint32_t type = HNDTYPE_WEAK_SHORT;
     uint32_t flags = (((ScanContext*) lp1)->concurrent) ? HNDGCF_ASYNC : HNDGCF_NORMAL;
 
     int uCPUindex = getSlotNumber((ScanContext*) lp1);
@@ -1403,7 +1392,7 @@ void Ref_CheckAlive(uint32_t condemned, uint32_t maxgen, uintptr_t lp1)
             {
                 HHANDLETABLE hTable = walk->pBuckets[i]->pTable[uCPUindex];
                 if (hTable)
-                    HndScanHandlesForGC(hTable, CheckPromoted, lp1, 0, types, ARRAY_SIZE(types), condemned, maxgen, flags);
+                    HndScanHandlesForGC(hTable, CheckPromoted, lp1, 0, &type, 1, condemned, maxgen, flags);
             }
         }
         walk = walk->pNext;
@@ -1446,9 +1435,6 @@ void Ref_UpdatePointers(uint32_t condemned, uint32_t maxgen, ScanContext* sc, Re
 #if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS) || defined(FEATURE_OBJCMARSHAL) || defined(FEATURE_NATIVEAOT)
         HNDTYPE_REFCOUNTED,
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL || FEATURE_NATIVEAOT
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-        HNDTYPE_WEAK_NATIVE_COM,
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
         HNDTYPE_SIZEDREF,
     };
 
@@ -1492,9 +1478,6 @@ void Ref_ScanHandlesForProfilerAndETW(uint32_t maxgen, uintptr_t lp1, handle_sca
 #if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS) || defined(FEATURE_OBJCMARSHAL) || defined(FEATURE_NATIVEAOT)
         HNDTYPE_REFCOUNTED,
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL || FEATURE_NATIVEAOT
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-        HNDTYPE_WEAK_NATIVE_COM,
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
         HNDTYPE_PINNED,
 //        HNDTYPE_VARIABLE,
 #ifdef FEATURE_ASYNC_PINNED_HANDLES
@@ -1648,9 +1631,6 @@ void Ref_AgeHandles(uint32_t condemned, uint32_t maxgen, uintptr_t lp1)
 #if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS) || defined(FEATURE_OBJCMARSHAL) || defined(FEATURE_NATIVEAOT)
         HNDTYPE_REFCOUNTED,
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL || FEATURE_NATIVEAOT
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-        HNDTYPE_WEAK_NATIVE_COM,
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
 #ifdef FEATURE_ASYNC_PINNED_HANDLES
         HNDTYPE_ASYNCPINNED,
 #endif
@@ -1693,9 +1673,6 @@ void Ref_RejuvenateHandles(uint32_t condemned, uint32_t maxgen, uintptr_t lp1)
 #if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS) || defined(FEATURE_OBJCMARSHAL) || defined(FEATURE_NATIVEAOT)
         HNDTYPE_REFCOUNTED,
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL || FEATURE_NATIVEAOT
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-        HNDTYPE_WEAK_NATIVE_COM,
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
 #ifdef FEATURE_ASYNC_PINNED_HANDLES
         HNDTYPE_ASYNCPINNED,
 #endif
@@ -1737,9 +1714,6 @@ void Ref_VerifyHandleTable(uint32_t condemned, uint32_t maxgen, ScanContext* sc)
 #if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS) || defined(FEATURE_OBJCMARSHAL) || defined(FEATURE_NATIVEAOT)
         HNDTYPE_REFCOUNTED,
 #endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS || FEATURE_OBJCMARSHAL || FEATURE_NATIVEAOT
-#if defined(FEATURE_COMINTEROP) || defined(FEATURE_COMWRAPPERS)
-        HNDTYPE_WEAK_NATIVE_COM,
-#endif // FEATURE_COMINTEROP || FEATURE_COMWRAPPERS
 #ifdef FEATURE_ASYNC_PINNED_HANDLES
         HNDTYPE_ASYNCPINNED,
 #endif

src/coreclr/inc/dacvars.h

@@ -162,6 +162,9 @@ DEFINE_DACVAR(UNKNOWN_POINTER_TYPE, dac__g_pThreadClass, ::g_pThreadClass)
 DEFINE_DACVAR(UNKNOWN_POINTER_TYPE, dac__g_pPredefinedArrayTypes, ::g_pPredefinedArrayTypes)
 DEFINE_DACVAR(UNKNOWN_POINTER_TYPE, dac__g_TypedReferenceMT, ::g_TypedReferenceMT)
 
+DEFINE_DACVAR(UNKNOWN_POINTER_TYPE, dac__g_pWeakReferenceClass, ::g_pWeakReferenceClass)
+DEFINE_DACVAR(UNKNOWN_POINTER_TYPE, dac__g_pWeakReferenceOfTClass, ::g_pWeakReferenceOfTClass)
+
 #ifdef FEATURE_COMINTEROP
 DEFINE_DACVAR(UNKNOWN_POINTER_TYPE, dac__g_pBaseCOMObject, ::g_pBaseCOMObject)
 #endif

src/coreclr/nativeaot/Runtime/ObjectLayout.h

@@ -136,5 +136,5 @@ static uintptr_t const MAX_STRING_LENGTH = 0x3FFFFFDF;
 class WeakReference : public Object
 {
 public:
-    uintptr_t    m_HandleAndKind;
+    uintptr_t    m_taggedHandle;
 };

src/coreclr/nativeaot/Runtime/gcrhenv.cpp

@@ -1181,10 +1181,15 @@ bool GCToEEInterface::EagerFinalized(Object* obj)
     // Managed code should not be running.
     ASSERT(GCHeapUtilities::GetGCHeap()->IsGCInProgressHelper());
 
+    // the lowermost 1 bit is reserved for storing additional info about the handle
+    const uintptr_t HandleTagBits = 1;
+
     WeakReference* weakRefObj = (WeakReference*)obj;
-    OBJECTHANDLE handle = (OBJECTHANDLE)(weakRefObj->m_HandleAndKind & ~(uintptr_t)1);
-    HandleType handleType = (weakRefObj->m_HandleAndKind & 1) ? HandleType::HNDTYPE_WEAK_LONG : HandleType::HNDTYPE_WEAK_SHORT;
-    weakRefObj->m_HandleAndKind &= (uintptr_t)1;
+    OBJECTHANDLE handle = (OBJECTHANDLE)(weakRefObj->m_taggedHandle & ~HandleTagBits);
+    _ASSERTE((weakRefObj->m_taggedHandle & 2) == 0);
+    HandleType handleType = (weakRefObj->m_taggedHandle & 1) ? HandleType::HNDTYPE_WEAK_LONG : HandleType::HNDTYPE_WEAK_SHORT;
+    // keep the bit that indicates whether this reference was tracking resurrection, clear the rest.
+    weakRefObj->m_taggedHandle &= (uintptr_t)1;
     GCHandleUtilities::GetGCHandleManager()->DestroyHandleOfType(handle, handleType);
     return true;
 }

src/coreclr/nativeaot/System.Private.CoreLib/src/System.Private.CoreLib.csproj

@@ -169,6 +169,7 @@
     <Compile Include="System\Collections\Generic\Comparer.NativeAot.cs" />
     <Compile Include="System\Collections\Generic\EqualityComparer.NativeAot.cs" />
     <Compile Include="System\Collections\Generic\EqualOnlyComparer.cs" />
+    <Compile Include="System\ComAwareWeakReference.NativeAot.cs" />
     <Compile Include="System\InvokeUtils.cs" />
     <Compile Include="System\IO\FileLoadException.NativeAot.cs" />
     <Compile Include="System\RuntimeMethodHandle.cs" />