[MSFT 17535796] On depoloymorphication, write the slot index discovered during GlobOpt into the ObjTypeSpecFldInfo as well as the opnd field. That way it will be copied into the set that supports the runtime equivalence check.

lib/Backend/GlobOptFields.cpp

@@ -1170,6 +1170,9 @@ GlobOpt::ProcessPropOpInTypeCheckSeq(IR::Instr* instr, IR::PropertySymOpnd *opnd
                 opnd->SetSlotIndex(slotIndex);
                 opnd->SetUsesAuxSlot(auxSlot);
 
+                opnd->GetObjTypeSpecInfo()->SetSlotIndex(slotIndex);
+                opnd->GetObjTypeSpecInfo()->SetUsesAuxSlot(auxSlot);
+
                 isSpecialized = true;
                 if (isTypeCheckedOut)
                 {

lib/Backend/ObjTypeSpecFldInfo.cpp

@@ -77,6 +77,14 @@ ObjTypeSpecFldInfo::TryDepolymorphication(JITTypeHolder type, uint16 slotIndex,
     }
 }
 
+void
+ObjTypeSpecFldInfo::SetUsesAuxSlot(bool usesAuxSlot)
+{
+    ObjTypeSpecFldInfoFlags flags = GetFlags();
+    flags.usesAuxSlot = usesAuxSlot;
+    m_data.flags = flags.flags;
+}
+
 bool
 ObjTypeSpecFldInfo::UsesAuxSlot() const
 {
@@ -200,6 +208,13 @@ ObjTypeSpecFldInfo::GetSlotIndex() const
     return m_data.slotIndex;
 }
 
+void
+ObjTypeSpecFldInfo::SetSlotIndex(uint16 slotIndex)
+{
+    Assert(m_data.slotIndex == Js::Constants::NoSlot || m_data.slotIndex == slotIndex);
+    m_data.slotIndex = slotIndex;
+}
+
 uint16
 ObjTypeSpecFldInfo::GetFixedFieldCount() const
 {

lib/Backend/ObjTypeSpecFldInfo.h

@@ -137,6 +137,7 @@ public:
         m_data.polymorphicInfoArray = polymorphicInfoArray->GetRaw();
     }
 
+    void SetUsesAuxSlot(bool usesAuxSlot);
     bool UsesAuxSlot() const;
     bool UsesAccessor() const;
     bool IsRootObjectNonConfigurableFieldLoad() const;
@@ -199,6 +200,7 @@ public:
 
     Js::PropertyId GetPropertyId() const;
     uint16 GetSlotIndex() const;
+    void SetSlotIndex(uint16 slotIndex);
     uint16 * GetSlotIndices() const;
     uint16 GetFixedFieldCount() const;