[Local GC] Move Weak Reference finalization out of the GC (#10676)

* [Local GC] Move Weak Reference finalization out of the GC

* Address two issues:
  1) Use GetGCSafeMethodTable instead of GetMethodTable, so that the
     mark bit is correctly masked off the object's method table pointer,
  2) Address code review feedback by re-inserting a missed call to
     GetCanonicalMethodTable and rename the new API to EagerFinalized to
     better illustrate its broader purpose.

* Repair the GC sample

1 files changed, 22 insertions, 0 deletions

diff --git a/src/vm/gcenv.ee.cpp b/src/vm/gcenv.ee.cpp
index f3c139e66d..a652359c4f 100644
--- a/src/vm/gcenv.ee.cpp
+++ b/src/vm/gcenv.ee.cpp
@@ -29,6 +29,15 @@
 #include "comcallablewrapper.h"
 #endif // FEATURE_COMINTEROP
 
+// the method table for the WeakReference class
+extern MethodTable* pWeakReferenceMT;
+
+// The canonical method table for WeakReference<T>
+extern MethodTable* pWeakReferenceOfTCanonMT;
+
+// Finalizes a weak reference directly.
+extern void FinalizeWeakReference(Object* obj);
+
 void GCToEEInterface::SuspendEE(SUSPEND_REASON reason)
 {
     WRAPPER_NO_CONTRACT;
@@ -1359,3 +1368,16 @@ bool GCToEEInterface::ShouldFinalizeObjectForUnload(AppDomain* pDomain, Object*
     // to move them to a new app domain instead of finalizing them here.
     return true;
 }
+
+bool GCToEEInterface::EagerFinalized(Object* obj)
+{
+    MethodTable* pMT = obj->GetGCSafeMethodTable();
+    if (pMT == pWeakReferenceMT ||
+        pMT->GetCanonicalMethodTable() == pWeakReferenceOfTCanonMT)
+    {
+        FinalizeWeakReference(obj);
+        return true;
+    }
+
+    return false;
+}