FB

Author: am11

src/coreclr/System.Private.CoreLib/src/System/Runtime/CompilerServices/CastHelpers.cs

@@ -523,8 +523,7 @@ private static void ArrayTypeCheck_Helper(object obj, void* elementType)
         {
             Debug.Assert(srcMT->IsNullable);
 
-            // If 'hasValue' is false, return null.
-            if (!Unsafe.As<byte, bool>(ref nullableData))
+            if (nullableData == 0)
                 return null;
 
             // Allocate a new instance of the T in Nullable<T>.
@@ -541,6 +540,9 @@ internal static object Box(MethodTable* typeMT, ref byte unboxedData)
             Debug.Assert(typeMT != null);
             Debug.Assert(typeMT->IsValueType);
 
+            // A null can be passed for boxing of a null ref. 
+            _ = Unsafe.ReadUnaligned<byte>(ref unboxedData); 
+
             object boxed = RuntimeTypeHandle.InternalAllocNoChecks(typeMT);
             if (typeMT->ContainsGCPointers)
             {

src/coreclr/System.Private.CoreLib/src/System/RuntimeHandles.cs

@@ -306,11 +306,11 @@ internal static object InternalAllocNoChecks(MethodTable* pMT)
             return InternalAllocNoChecks_FastPath(pMT) ?? InternalAllocNoChecksWorker(pMT);
 
             [MethodImpl(MethodImplOptions.NoInlining)]
-            static object? InternalAllocNoChecksWorker(MethodTable* pMT)
+            static object InternalAllocNoChecksWorker(MethodTable* pMT)
             {
                 object? result = null;
                 InternalAllocNoChecks(pMT, ObjectHandleOnStack.Create(ref result));
-                return result;
+                return result!;
             }
         }
 

src/coreclr/vm/object.cpp

@@ -395,7 +395,7 @@ void CopyValueClassUnchecked(void* dest, void* src, MethodTable *pMT)
 // Copy value class into the argument specified by the argDest.
 // The destOffset is nonzero when copying values into Nullable<T>, it is the offset
 // of the T value inside of the Nullable<T>
-void STDCALL CopyValueClassArgUnchecked(ArgDestination *argDest, void* src, MethodTable *pMT, int destOffset)
+void CopyValueClassArgUnchecked(ArgDestination *argDest, void* src, MethodTable *pMT, int destOffset)
 {
     STATIC_CONTRACT_NOTHROW;
     STATIC_CONTRACT_GC_NOTRIGGER;

src/coreclr/vm/object.h

@@ -494,7 +494,7 @@ inline void ClearObjectReference(OBJECTREF* dst)
 // CopyValueClass sets a value class field
 
 void CopyValueClassUnchecked(void* dest, void* src, MethodTable *pMT);
-void STDCALL CopyValueClassArgUnchecked(ArgDestination *argDest, void* src, MethodTable *pMT, int destOffset);
+void CopyValueClassArgUnchecked(ArgDestination *argDest, void* src, MethodTable *pMT, int destOffset);
 
 inline void InitValueClass(void *dest, MethodTable *pMT)
 {

src/coreclr/vm/runtimehandles.cpp

@@ -1154,6 +1154,11 @@ FCIMPL1(Object*, RuntimeTypeHandle::InternalAllocNoChecks_FastPath, MethodTable*
         return NULL;
     }
 
+    if (pMT->HasFinalizer())
+    {
+        return NULL;
+    }
+
 #ifdef FEATURE_64BIT_ALIGNMENT
     if (pMT->RequiresAlign8())
     {