- implemented the backend for dynamic arrays. Still needs thorough testing but it should be complete.

- use a memory arena to store flat pointers so that the messed up cleanup can be avoided by deallocating this in bulk.
- added a new SO opcode to the VM to execute a write barrier. This is necessary for all objects that are not linked into one global table, i.e. everything except thinkers and class types.
- always use the cheaper LOS opcode for reading pointers to classes and defaults because these cannot be destroyed during normal operation.
- removed the pointless validation from String.Mid. If the values are read as unsigned the internal validation of FString::Mid will automatically ensure proper results.

src/dobject.cpp

@@ -397,6 +397,23 @@ size_t DObject::PropagateMark()
 			GC::Mark((DObject **)((BYTE *)this + *offsets));
 			offsets++;
 		}
+
+		offsets = info->ArrayPointers;
+		if (offsets == NULL)
+		{
+			const_cast<PClass *>(info)->BuildArrayPointers();
+			offsets = info->ArrayPointers;
+		}
+		while (*offsets != ~(size_t)0)
+		{
+			auto aray = (TArray<DObject*>*)((BYTE *)this + *offsets);
+			for (auto &p : *aray)
+			{
+				GC::Mark(&p);
+			}
+			offsets++;
+		}
+
 		return info->Size;
 	}
 	return 0;
@@ -427,6 +444,28 @@ size_t DObject::PointerSubstitution (DObject *old, DObject *notOld)
 		}
 		offsets++;
 	}
+
+	offsets = info->ArrayPointers;
+	if (offsets == NULL)
+	{
+		const_cast<PClass *>(info)->BuildArrayPointers();
+		offsets = info->ArrayPointers;
+	}
+	while (*offsets != ~(size_t)0)
+	{
+		auto aray = (TArray<DObject*>*)((BYTE *)this + *offsets);
+		for (auto &p : *aray)
+		{
+			if (p == old)
+			{
+				p = notOld;
+				changed++;
+			}
+		}
+		offsets++;
+	}
+
+
 	return changed;
 }
 

src/dobjtype.cpp

@@ -65,6 +65,7 @@ EXTERN_CVAR(Bool, strictdecorate);
 
 // PUBLIC DATA DEFINITIONS -------------------------------------------------
 
+FMemArena FlatpointerArena;	// stores the flat pointers because freeing them individually is rather messy.
 FNamespaceManager Namespaces;
 
 FTypeTable TypeTable;
@@ -99,7 +100,7 @@ PPointer *TypeVoidPtr;
 
 // PRIVATE DATA DEFINITIONS ------------------------------------------------
 
-// A harmless non-NULL FlatPointer for classes without pointers.
+// A harmless non-nullptr FlatPointer for classes without pointers.
 static const size_t TheEnd = ~(size_t)0;
 
 // CODE --------------------------------------------------------------------
@@ -118,7 +119,7 @@ void DumpTypeTable()
 	{
 		int len = 0;
 		Printf("%4zu:", i);
-		for (PType *ty = TypeTable.TypeHash[i]; ty != NULL; ty = ty->HashNext)
+		for (PType *ty = TypeTable.TypeHash[i]; ty != nullptr; ty = ty->HashNext)
 		{
 			Printf(" -> %s", ty->DescriptiveName());
 			len++;
@@ -161,7 +162,7 @@ IMPLEMENT_CLASS(PClassType, false, false)
 //==========================================================================
 
 PClassType::PClassType()
-: TypeTableType(NULL)
+: TypeTableType(nullptr)
 {
 }
 
@@ -211,7 +212,7 @@ IMPLEMENT_POINTERS_END
 //==========================================================================
 
 PType::PType(unsigned int size, unsigned int align)
-: Size(size), Align(align), HashNext(NULL)
+: Size(size), Align(align), HashNext(nullptr)
 {
 	mDescriptiveName = "Type";
 	loadOp = OP_NOP;
@@ -286,6 +287,10 @@ void PType::SetPointer(void *base, unsigned offset, TArray<size_t> *stroffs) con
 {
 }
 
+void PType::SetPointerArray(void *base, unsigned offset, TArray<size_t> *stroffs) const
+{
+}
+
 //==========================================================================
 //
 // PType :: InitializeValue
@@ -831,7 +836,7 @@ PBool::PBool()
 	MemberOnly = false;
 	// Override the default max set by PInt's constructor
 	PSymbolConstNumeric *maxsym = static_cast<PSymbolConstNumeric *>(Symbols.FindSymbol(NAME_Max, false));
-	assert(maxsym != NULL && maxsym->IsKindOf(RUNTIME_CLASS(PSymbolConstNumeric)));
+	assert(maxsym != nullptr && maxsym->IsKindOf(RUNTIME_CLASS(PSymbolConstNumeric)));
 	maxsym->Value = 1;
 }
 
@@ -1147,7 +1152,7 @@ bool PString::ReadValue(FSerializer &ar, const char *key, void *addr) const
 void PString::SetDefaultValue(void *base, unsigned offset, TArray<FTypeAndOffset> *special) const
 {
 	if (base != nullptr) new((BYTE *)base + offset) FString;
-	if (special != NULL)
+	if (special != nullptr)
 	{
 		special->Push(std::make_pair(this, offset));
 	}
@@ -1415,7 +1420,7 @@ IMPLEMENT_POINTERS_END
 //==========================================================================
 
 PPointer::PPointer()
-: PBasicType(sizeof(void *), alignof(void *)), PointedType(NULL), IsConst(false)
+: PBasicType(sizeof(void *), alignof(void *)), PointedType(nullptr), IsConst(false)
 {
 	mDescriptiveName = "NullPointer";
 	SetOps();
@@ -1442,8 +1447,9 @@ PPointer::PPointer(PType *pointsat, bool isconst)
 
 void PPointer::SetOps()
 {
-	storeOp = OP_SP;
 	loadOp = (PointedType && PointedType->IsKindOf(RUNTIME_CLASS(PClass))) ? OP_LO : OP_LP;
+	// Non-destroyed thinkers are always guaranteed to be linked into the thinker chain so we don't need the write barrier for them.
+	storeOp = (loadOp == OP_LO && !static_cast<PClass*>(PointedType)->IsDescendantOf(RUNTIME_CLASS(DThinker))) ? OP_SO : OP_SP;
 	moveOp = OP_MOVEA;
 	RegType = REGT_POINTER;
 }
@@ -1476,7 +1482,7 @@ void PPointer::GetTypeIDs(intptr_t &id1, intptr_t &id2) const
 
 //==========================================================================
 //
-// PPointer :: SetDefaultValue
+// PPointer :: SetPointer
 //
 //==========================================================================
 
@@ -1547,7 +1553,7 @@ PPointer *NewPointer(PType *type, bool isconst)
 {
 	size_t bucket;
 	PType *ptype = TypeTable.FindType(RUNTIME_CLASS(PPointer), (intptr_t)type, isconst ? 1 : 0, &bucket);
-	if (ptype == NULL)
+	if (ptype == nullptr)
 	{
 		ptype = new PPointer(type, isconst);
 		TypeTable.AddType(ptype, RUNTIME_CLASS(PPointer), (intptr_t)type, isconst ? 1 : 0, bucket);
@@ -1606,18 +1612,6 @@ IMPLEMENT_POINTERS_START(PClassPointer)
 	IMPLEMENT_POINTER(ClassRestriction)
 IMPLEMENT_POINTERS_END
 
-//==========================================================================
-//
-// PClassPointer - Default Constructor
-//
-//==========================================================================
-
-PClassPointer::PClassPointer()
-: PPointer(RUNTIME_CLASS(PClass)), ClassRestriction(NULL)
-{
-	mDescriptiveName = "ClassPointer";
-}
-
 //==========================================================================
 //
 // PClassPointer - Parameterized Constructor
@@ -1629,6 +1623,10 @@ PClassPointer::PClassPointer(PClass *restrict)
 {
 	if (restrict) mDescriptiveName.Format("ClassPointer<%s>", restrict->TypeName.GetChars());
 	else mDescriptiveName = "ClassPointer";
+	// class pointers do not need write barriers because all classes are stored in the global type table and won't get collected.
+	// This means we can use the cheapoer non-barriered opcodes here.
+	loadOp = OP_LOS;
+	storeOp = OP_SP;
 }
 
 //==========================================================================
@@ -1683,7 +1681,7 @@ PClassPointer *NewClassPointer(PClass *restrict)
 {
 	size_t bucket;
 	PType *ptype = TypeTable.FindType(RUNTIME_CLASS(PClassPointer), (intptr_t)RUNTIME_CLASS(PClass), (intptr_t)restrict, &bucket);
-	if (ptype == NULL)
+	if (ptype == nullptr)
 	{
 		ptype = new PClassPointer(restrict);
 		TypeTable.AddType(ptype, RUNTIME_CLASS(PClassPointer), (intptr_t)RUNTIME_CLASS(PClass), (intptr_t)restrict, bucket);
@@ -1739,7 +1737,7 @@ PEnum *NewEnum(FName name, PTypeBase *outer)
 	size_t bucket;
 	if (outer == nullptr) outer = Namespaces.GlobalNamespace;
 	PType *etype = TypeTable.FindType(RUNTIME_CLASS(PEnum), (intptr_t)outer, (intptr_t)name, &bucket);
-	if (etype == NULL)
+	if (etype == nullptr)
 	{
 		etype = new PEnum(name, outer);
 		TypeTable.AddType(etype, RUNTIME_CLASS(PEnum), (intptr_t)outer, (intptr_t)name, bucket);
@@ -1762,7 +1760,7 @@ IMPLEMENT_POINTERS_END
 //==========================================================================
 
 PArray::PArray()
-: ElementType(NULL), ElementCount(0)
+: ElementType(nullptr), ElementCount(0)
 {
 	mDescriptiveName = "Array";
 }
@@ -1902,7 +1900,7 @@ PArray *NewArray(PType *type, unsigned int count)
 {
 	size_t bucket;
 	PType *atype = TypeTable.FindType(RUNTIME_CLASS(PArray), (intptr_t)type, count, &bucket);
-	if (atype == NULL)
+	if (atype == nullptr)
 	{
 		atype = new PArray(type, count);
 		TypeTable.AddType(atype, RUNTIME_CLASS(PArray), (intptr_t)type, count, bucket);
@@ -1976,7 +1974,7 @@ PResizableArray *NewResizableArray(PType *type)
 {
 	size_t bucket;
 	PType *atype = TypeTable.FindType(RUNTIME_CLASS(PResizableArray), (intptr_t)type, 0, &bucket);
-	if (atype == NULL)
+	if (atype == nullptr)
 	{
 		atype = new PResizableArray(type);
 		TypeTable.AddType(atype, RUNTIME_CLASS(PResizableArray), (intptr_t)type, 0, bucket);
@@ -1999,7 +1997,7 @@ IMPLEMENT_POINTERS_END
 //==========================================================================
 
 PDynArray::PDynArray()
-: ElementType(NULL)
+: ElementType(nullptr)
 {
 	mDescriptiveName = "DynArray";
 	Size = sizeof(FArray);
@@ -2046,6 +2044,152 @@ void PDynArray::GetTypeIDs(intptr_t &id1, intptr_t &id2) const
 	id2 = 0;
 }
 
+//==========================================================================
+//
+// PDynArray :: InitializeValue
+//
+//==========================================================================
+
+void PDynArray::InitializeValue(void *addr, const void *deff) const
+{
+	const FArray *def = (const FArray*)deff;
+	FArray *aray = (FArray*)addr;
+
+	if (def == nullptr || def->Count == 0)
+	{
+		// Empty arrays do not need construction.
+		*aray = { nullptr, 0, 0 };
+	}
+	else if (ElementType->GetRegType() != REGT_STRING)
+	{
+		// These are just integral values which can be done without any constructor hackery.
+		size_t blocksize = ElementType->Size * def->Count;
+		aray->Array = M_Malloc(blocksize);
+		memcpy(aray->Array, def->Array, blocksize);
+		aray->Most = aray->Count = def->Count;
+	}
+	else
+	{
+		// non-empty string arrays require explicit construction.
+		new(addr) TArray<FString>(*(TArray<FString>*)def);
+	}
+}
+
+//==========================================================================
+//
+// PDynArray :: DestroyValue
+//
+//==========================================================================
+
+void PDynArray::DestroyValue(void *addr) const
+{
+	FArray *aray = (FArray*)addr;
+
+	if (aray->Array != nullptr)
+	{
+		if (ElementType->GetRegType() != REGT_STRING)
+		{
+			M_Free(aray->Array);
+		}
+		else
+		{
+			// Damn those cursed strings again. :(
+			((TArray<FString>*)addr)->~TArray<FString>();
+		}
+	}
+	aray->Count = aray->Most = 0;
+	aray->Array = nullptr;
+}
+
+//==========================================================================
+//
+// PDynArray :: SetDefaultValue
+//
+//==========================================================================
+
+void PDynArray::SetDefaultValue(void *base, unsigned offset, TArray<FTypeAndOffset> *special) const
+{
+	memset((char*)base + offset, 0, sizeof(FArray));	// same as constructing an empty array.
+	if (special != nullptr)
+	{
+		special->Push(std::make_pair(this, offset));
+	}
+}
+
+//==========================================================================
+//
+// PDynArray :: SetPointer
+//
+//==========================================================================
+
+void PDynArray::SetPointerArray(void *base, unsigned offset, TArray<size_t> *special) const
+{
+	if (ElementType->IsKindOf(RUNTIME_CLASS(PPointer)) && static_cast<PPointer*>(ElementType)->PointedType->IsKindOf(RUNTIME_CLASS(PClass)))
+	{
+		// Add to the list of pointer arrays for this class.
+		special->Push(offset);
+	}
+}
+
+//==========================================================================
+//
+// PDynArray :: WriteValue
+//
+//==========================================================================
+
+void PDynArray::WriteValue(FSerializer &ar, const char *key, const void *addr) const
+{
+	FArray *aray = (FArray*)addr;
+	if (aray->Count > 0)
+	{
+		if (ar.BeginArray(key))
+		{
+			const BYTE *addrb = (const BYTE *)aray->Array;
+			for (unsigned i = 0; i < aray->Count; ++i)
+			{
+				ElementType->WriteValue(ar, nullptr, addrb);
+				addrb += ElementType->Size;
+			}
+			ar.EndArray();
+		}
+	}
+}
+
+//==========================================================================
+//
+// PDynArray :: ReadValue
+//
+//==========================================================================
+
+bool PDynArray::ReadValue(FSerializer &ar, const char *key, void *addr) const
+{
+	FArray *aray = (FArray*)addr;
+	DestroyValue(addr);	// note that even after calling this we still got a validly constructed empty array.
+
+	if (ar.BeginArray(key))
+	{
+		bool readsomething = false;
+		unsigned count = ar.ArraySize();
+
+		size_t blocksize = ElementType->Size * count;
+		aray->Array = M_Malloc(blocksize);
+		memset(aray->Array, 0, blocksize);
+		aray->Most = aray->Count = count;
+
+		BYTE *addrb = (BYTE *)aray->Array;
+		for (unsigned i = 0; i<count; i++)
+		{
+			// Strings must be constructed first.
+			if (ElementType->GetRegType() == REGT_STRING) new(addrb) FString;
+			readsomething |= ElementType->ReadValue(ar, nullptr, addrb);
+			addrb += ElementType->Size;
+		}
+		ar.EndArray();
+		return readsomething;
+	}
+	return false;
+}
+
 //==========================================================================
 //
 // NewDynArray
@@ -2059,7 +2203,7 @@ PDynArray *NewDynArray(PType *type)
 {
 	size_t bucket;
 	PType *atype = TypeTable.FindType(RUNTIME_CLASS(PDynArray), (intptr_t)type, 0, &bucket);
-	if (atype == NULL)
+	if (atype == nullptr)
 	{
 		FString backingname;
 
@@ -2109,7 +2253,7 @@ IMPLEMENT_POINTERS_END
 //==========================================================================
 
 PMap::PMap()
-: KeyType(NULL), ValueType(NULL)
+: KeyType(nullptr), ValueType(nullptr)
 {
 	mDescriptiveName = "Map";
 	Size = sizeof(FMap);
@@ -2169,7 +2313,7 @@ PMap *NewMap(PType *keytype, PType *valuetype)
 {
 	size_t bucket;
 	PType *maptype = TypeTable.FindType(RUNTIME_CLASS(PMap), (intptr_t)keytype, (intptr_t)valuetype, &bucket);
-	if (maptype == NULL)
+	if (maptype == nullptr)
 	{
 		maptype = new PMap(keytype, valuetype);
 		TypeTable.AddType(maptype, RUNTIME_CLASS(PMap), (intptr_t)keytype, (intptr_t)valuetype, bucket);
@@ -2308,7 +2452,7 @@ bool PStruct::ReadFields(FSerializer &ar, void *addr) const
 		foundsomething = true;
 
 		const PSymbol *sym = Symbols.FindSymbol(FName(label, true), true);
-		if (sym == NULL)
+		if (sym == nullptr)
 		{
 			DPrintf(DMSG_ERROR, "Cannot find field %s in %s\n",
 				label, TypeName.GetChars());
@@ -2332,7 +2476,7 @@ bool PStruct::ReadFields(FSerializer &ar, void *addr) const
 // PStruct :: AddField
 //
 // Appends a new field to the end of a struct. Returns either the new field
-// or NULL if a symbol by that name already exists.
+// or nullptr if a symbol by that name already exists.
 //
 //==========================================================================
 
@@ -2350,10 +2494,10 @@ PField *PStruct::AddField(FName name, PType *type, DWORD flags)
 	// its fields.
 	Align = MAX(Align, type->Align);
 
-	if (Symbols.AddSymbol(field) == NULL)
+	if (Symbols.AddSymbol(field) == nullptr)
 	{ // name is already in use
 		delete field;
-		return NULL;
+		return nullptr;
 	}
 	Fields.Push(field);
 
@@ -2365,7 +2509,7 @@ PField *PStruct::AddField(FName name, PType *type, DWORD flags)
 // PStruct :: AddField
 //
 // Appends a new native field to the struct. Returns either the new field
-// or NULL if a symbol by that name already exists.
+// or nullptr if a symbol by that name already exists.
 //
 //==========================================================================
 
@@ -2408,7 +2552,7 @@ PStruct *NewStruct(FName name, PTypeBase *outer)
 	size_t bucket;
 	if (outer == nullptr) outer = Namespaces.GlobalNamespace;
 	PType *stype = TypeTable.FindType(RUNTIME_CLASS(PStruct), (intptr_t)outer, (intptr_t)name, &bucket);
-	if (stype == NULL)
+	if (stype == nullptr)
 	{
 		stype = new PStruct(name, outer);
 		TypeTable.AddType(stype, RUNTIME_CLASS(PStruct), (intptr_t)outer, (intptr_t)name, bucket);
@@ -2447,7 +2591,7 @@ PNativeStruct *NewNativeStruct(FName name, PTypeBase *outer)
 	size_t bucket;
 	if (outer == nullptr) outer = Namespaces.GlobalNamespace;
 	PType *stype = TypeTable.FindType(RUNTIME_CLASS(PNativeStruct), (intptr_t)outer, (intptr_t)name, &bucket);
-	if (stype == NULL)
+	if (stype == nullptr)
 	{
 		stype = new PNativeStruct(name, outer);
 		TypeTable.AddType(stype, RUNTIME_CLASS(PNativeStruct), (intptr_t)outer, (intptr_t)name, bucket);
@@ -2466,7 +2610,7 @@ IMPLEMENT_CLASS(PField, false, false)
 //==========================================================================
 
 PField::PField()
-: PSymbol(NAME_None), Offset(0), Type(NULL), Flags(0)
+: PSymbol(NAME_None), Offset(0), Type(nullptr), Flags(0)
 {
 }
 
@@ -2599,7 +2743,7 @@ PPrototype *NewPrototype(const TArray<PType *> &rettypes, const TArray<PType *>
 {
 	size_t bucket;
 	PType *proto = TypeTable.FindType(RUNTIME_CLASS(PPrototype), (intptr_t)&argtypes, (intptr_t)&rettypes, &bucket);
-	if (proto == NULL)
+	if (proto == nullptr)
 	{
 		proto = new PPrototype(rettypes, argtypes);
 		TypeTable.AddType(proto, RUNTIME_CLASS(PPrototype), (intptr_t)&argtypes, (intptr_t)&rettypes, bucket);
@@ -2689,7 +2833,7 @@ IMPLEMENT_POINTERS_END
 
 static void RecurseWriteFields(const PClass *type, FSerializer &ar, const void *addr)
 {
-	if (type != NULL)
+	if (type != nullptr)
 	{
 		RecurseWriteFields(type->ParentClass, ar, addr);
 		// Don't write this part if it has no non-transient variables
@@ -2773,7 +2917,7 @@ bool PClass::ReadAllFields(FSerializer &ar, void *addr) const
 		{
 			// Only read it if the type is related to this one.
 			const PClass *parent;
-			for (parent = this; parent != NULL; parent = parent->ParentClass)
+			for (parent = this; parent != nullptr; parent = parent->ParentClass)
 			{
 				if (parent == type)
 				{
@@ -2835,7 +2979,7 @@ void PClass::StaticInit ()
 
 	FAutoSegIterator probe(CRegHead, CRegTail);
 
-	while (*++probe != NULL)
+	while (*++probe != nullptr)
 	{
 		((ClassReg *)*probe)->RegisterClass ();
 	}
@@ -2859,16 +3003,12 @@ void PClass::StaticInit ()
 //
 // PClass :: StaticShutdown											STATIC
 //
-// Frees FlatPointers belonging to all classes. Only really needed to avoid
+// Frees all static class data.
-// memory leak warnings at exit.
 //
 //==========================================================================
 
 void PClass::StaticShutdown ()
 {
-	TArray<size_t *> uniqueFPs(64);
-	unsigned int i, j;
-
 	// delete all variables containing pointers to script functions.
 	for (auto p : FunctionPtrList)
 	{
@@ -2876,7 +3016,8 @@ void PClass::StaticShutdown ()
 	}
 	FunctionPtrList.Clear();
 
-	// Make a full garbage collection here so that all destroyed but uncollected higher level objects that still exist can be properly taken down.
+	// Make a full garbage collection here so that all destroyed but uncollected higher level objects 
+	// that still exist are properly taken down before the low level data is deleted.
 	GC::FullGC();
 
 	// From this point onward no scripts may be called anymore because the data needed by the VM is getting deleted now.
@@ -2886,33 +3027,7 @@ void PClass::StaticShutdown ()
 	// Unless something went wrong, anything left here should be class and type objects only, which do not own any scripts.
 	TypeTable.Clear();
 	Namespaces.ReleaseSymbols();
-
+	FlatpointerArena.FreeAllBlocks();
-	for (i = 0; i < PClass::AllClasses.Size(); ++i)
-	{
-		PClass *type = PClass::AllClasses[i];
-		PClass::AllClasses[i] = NULL;
-		if (type->FlatPointers != &TheEnd && type->FlatPointers != type->Pointers)
-		{
-			// FlatPointers are shared by many classes, so we must check for
-			// duplicates and only delete those that are unique.
-			for (j = 0; j < uniqueFPs.Size(); ++j)
-			{
-				if (type->FlatPointers == uniqueFPs[j])
-				{
-					break;
-				}
-			}
-			if (j == uniqueFPs.Size())
-			{
-				uniqueFPs.Push(const_cast<size_t *>(type->FlatPointers));
-			}
-		}
-		type->Destroy();
-	}
-	for (i = 0; i < uniqueFPs.Size(); ++i)
-	{
-		delete[] uniqueFPs[i];
-	}
 	bShutdown = true;
 
 	AllClasses.Clear();
@@ -2946,7 +3061,7 @@ void PClass::StaticBootstrap()
 	PClassClass *cls = new PClassClass;
 	PClass::RegistrationInfo.SetupClass(cls);
 
-	// The PClassClass constructor initialized these to NULL, because the
+	// The PClassClass constructor initialized these to nullptr, because the
 	// PClass metadata had not been created yet. Now it has, so we know what
 	// they should be and can insert them into the type table successfully.
 	clscls->TypeTableType = cls;
@@ -2971,6 +3086,7 @@ PClass::PClass()
 	ParentClass = nullptr;
 	Pointers = nullptr;
 	FlatPointers = nullptr;
+	ArrayPointers = nullptr;
 	HashNext = nullptr;
 	Defaults = nullptr;
 	bRuntimeClass = false;
@@ -2990,10 +3106,10 @@ PClass::PClass()
 
 PClass::~PClass()
 {
-	if (Defaults != NULL)
+	if (Defaults != nullptr)
 	{
 		M_Free(Defaults);
-		Defaults = NULL;
+		Defaults = nullptr;
 	}
 }
 
@@ -3020,7 +3136,7 @@ PClass *ClassReg::RegisterClass()
 	};
 
 	// Skip classes that have already been registered
-	if (MyClass != NULL)
+	if (MyClass != nullptr)
 	{
 		return MyClass;
 	}
@@ -3059,7 +3175,7 @@ PClass *ClassReg::RegisterClass()
 
 void ClassReg::SetupClass(PClass *cls)
 {
-	assert(MyClass == NULL);
+	assert(MyClass == nullptr);
 	MyClass = cls;
 	cls->TypeName = FName(Name+1);
 	cls->Size = SizeOf;
@@ -3082,7 +3198,7 @@ void PClass::InsertIntoHash ()
 	PType *found;
 
 	found = TypeTable.FindType(RUNTIME_CLASS(PClass), 0, TypeName, &bucket);
-	if (found != NULL)
+	if (found != nullptr)
 	{ // This type has already been inserted
 		I_Error("Tried to register class '%s' more than once.\n", TypeName.GetChars());
 	}
@@ -3102,14 +3218,14 @@ void PClass::InsertIntoHash ()
 
 const PClass *PClass::FindParentClass(FName name) const
 {
-	for (const PClass *type = this; type != NULL; type = type->ParentClass)
+	for (const PClass *type = this; type != nullptr; type = type->ParentClass)
 	{
 		if (type->TypeName == name)
 		{
 			return type;
 		}
 	}
-	return NULL;
+	return nullptr;
 }
 
 //==========================================================================
@@ -3124,9 +3240,9 @@ PClass *PClass::FindClass (FName zaname)
 {
 	if (zaname == NAME_None)
 	{
-		return NULL;
+		return nullptr;
 	}
-	return static_cast<PClass *>(TypeTable.FindType(RUNTIME_CLASS(PClass), 0, zaname, NULL));
+	return static_cast<PClass *>(TypeTable.FindType(RUNTIME_CLASS(PClass), 0, zaname, nullptr));
 }
 
 //==========================================================================
@@ -3140,10 +3256,10 @@ PClass *PClass::FindClass (FName zaname)
 DObject *PClass::CreateNew() const
 {
 	BYTE *mem = (BYTE *)M_Malloc (Size);
-	assert (mem != NULL);
+	assert (mem != nullptr);
 
 	// Set this object's defaults before constructing it.
-	if (Defaults != NULL)
+	if (Defaults != nullptr)
 		memcpy (mem, Defaults, Size);
 	else
 		memset (mem, 0, Size);
@@ -3170,7 +3286,7 @@ void PClass::InitializeSpecials(void *addr, void *defaults) const
 	{
 		return;
 	}
-	assert(ParentClass != NULL);
+	assert(ParentClass != nullptr);
 	ParentClass->InitializeSpecials(addr, defaults);
 	for (auto tao : SpecialInits)
 	{
@@ -3195,7 +3311,7 @@ void PClass::DestroySpecials(void *addr) const
 	{
 		return;
 	}
-	assert(ParentClass != NULL);
+	assert(ParentClass != nullptr);
 	ParentClass->DestroySpecials(addr);
 	for (auto tao : SpecialInits)
 	{
@@ -3231,7 +3347,7 @@ void PClass::InitializeDefaults()
 {
 	if (IsKindOf(RUNTIME_CLASS(PClassActor)))
 	{
-		assert(Defaults == NULL);
+		assert(Defaults == nullptr);
 		Defaults = (BYTE *)M_Malloc(Size);
 
 		// run the constructor on the defaults to set the vtbl pointer which is needed to run class-aware functions on them.
@@ -3248,7 +3364,7 @@ void PClass::InitializeDefaults()
 
 
 		// Copy the defaults from the parent but leave the DObject part alone because it contains important data.
-		if (ParentClass->Defaults != NULL)
+		if (ParentClass->Defaults != nullptr)
 		{
 			memcpy(Defaults + sizeof(DObject), ParentClass->Defaults + sizeof(DObject), ParentClass->Size - sizeof(DObject));
 			if (Size > ParentClass->Size)
@@ -3265,7 +3381,7 @@ void PClass::InitializeDefaults()
 	if (bRuntimeClass)
 	{
 		// Copy parent values from the parent defaults.
-		assert(ParentClass != NULL);
+		assert(ParentClass != nullptr);
 		ParentClass->InitializeSpecials(Defaults, ParentClass->Defaults);
 
 		for (const PField *field : Fields)
@@ -3404,14 +3520,14 @@ PClass *PClass::FindClassTentative(FName name)
 {
 	if (name == NAME_None)
 	{
-		return NULL;
+		return nullptr;
 	}
 	size_t bucket;
 
 	PType *found = TypeTable.FindType(RUNTIME_CLASS(PClass),
 		/*FIXME:Outer*/0, name, &bucket);
 
-	if (found != NULL)
+	if (found != nullptr)
 	{
 		return static_cast<PClass *>(found);
 	}
@@ -3484,14 +3600,14 @@ int PClass::FindVirtualIndex(FName name, PPrototype *proto)
 
 void PClass::BuildFlatPointers ()
 {
-	if (FlatPointers != NULL)
+	if (FlatPointers != nullptr)
 	{ // Already built: Do nothing.
 		return;
 	}
-	else if (ParentClass == NULL)
+	else if (ParentClass == nullptr)
 	{ // No parent (i.e. DObject: FlatPointers is the same as Pointers.
-		if (Pointers == NULL)
+		if (Pointers == nullptr)
-		{ // No pointers: Make FlatPointers a harmless non-NULL.
+		{ // No pointers: Make FlatPointers a harmless non-nullptr.
 			FlatPointers = &TheEnd;
 		}
 		else
@@ -3536,7 +3652,7 @@ void PClass::BuildFlatPointers ()
 			{ }
 
 			// Concatenate them into a new array
-			size_t *flat = new size_t[numPointers + numSuperPointers + ScriptPointers.Size() + 1];
+			size_t *flat = (size_t*)FlatpointerArena.Alloc(sizeof(size_t) * (numPointers + numSuperPointers + ScriptPointers.Size() + 1));
 			if (numSuperPointers > 0)
 			{
 				memcpy (flat, ParentClass->FlatPointers, sizeof(size_t)*numSuperPointers);
@@ -3555,6 +3671,68 @@ void PClass::BuildFlatPointers ()
 	}
 }
 
+//==========================================================================
+//
+// PClass :: BuildArrayPointers
+//
+// same as above, but creates a list to dynamic object arrays
+//
+//==========================================================================
+
+void PClass::BuildArrayPointers()
+{
+	if (ArrayPointers != nullptr)
+	{ // Already built: Do nothing.
+		return;
+	}
+	else if (ParentClass == nullptr)
+	{ // No parent (i.e. DObject: FlatPointers is the same as Pointers.
+		ArrayPointers = &TheEnd;
+	}
+	else
+	{
+		ParentClass->BuildArrayPointers();
+
+		TArray<size_t> ScriptPointers;
+
+		// Collect all arrays to pointers in scripted fields.
+		for (auto field : Fields)
+		{
+			if (!(field->Flags & VARF_Native))
+			{
+				field->Type->SetPointerArray(Defaults, unsigned(field->Offset), &ScriptPointers);
+			}
+		}
+
+		if (ScriptPointers.Size() == 0)
+		{ // No new pointers: Just use the same ArrayPointers as the parent.
+			ArrayPointers = ParentClass->ArrayPointers;
+		}
+		else
+		{ // New pointers: Create a new FlatPointers array and add them.
+			int numSuperPointers;
+
+			// Count pointers defined by superclasses.
+			for (numSuperPointers = 0; ParentClass->ArrayPointers[numSuperPointers] != ~(size_t)0; numSuperPointers++)
+			{
+			}
+
+			// Concatenate them into a new array
+			size_t *flat = (size_t*)FlatpointerArena.Alloc(sizeof(size_t) * (numSuperPointers + ScriptPointers.Size() + 1));
+			if (numSuperPointers > 0)
+			{
+				memcpy(flat, ParentClass->ArrayPointers, sizeof(size_t)*numSuperPointers);
+			}
+			if (ScriptPointers.Size() > 0)
+			{
+				memcpy(flat + numSuperPointers, &ScriptPointers[0], sizeof(size_t) * ScriptPointers.Size());
+			}
+			flat[numSuperPointers + ScriptPointers.Size()] = ~(size_t)0;
+			ArrayPointers = flat;
+		}
+	}
+}
+
 //==========================================================================
 //
 // PClass :: NativeClass
@@ -3604,18 +3782,18 @@ void PClass::FindFunction(VMFunction **pptr, FName clsname, FName funcname)
 PType *FTypeTable::FindType(PClass *metatype, intptr_t parm1, intptr_t parm2, size_t *bucketnum)
 {
 	size_t bucket = Hash(metatype, parm1, parm2) % HASH_SIZE;
-	if (bucketnum != NULL)
+	if (bucketnum != nullptr)
 	{
 		*bucketnum = bucket;
 	}
-	for (PType *type = TypeHash[bucket]; type != NULL; type = type->HashNext)
+	for (PType *type = TypeHash[bucket]; type != nullptr; type = type->HashNext)
 	{
 		if (type->GetClass()->TypeTableType == metatype && type->IsMatch(parm1, parm2))
 		{
 			return type;
 		}
 	}
-	return NULL;
+	return nullptr;
 }
 
 //==========================================================================
@@ -3630,13 +3808,13 @@ PType *FTypeTable::FindType(PClass *metatype, intptr_t parm1, intptr_t parm2, si
 
 void FTypeTable::ReplaceType(PType *newtype, PType *oldtype, size_t bucket)
 {
-	for (PType **type_p = &TypeHash[bucket]; *type_p != NULL; type_p = &(*type_p)->HashNext)
+	for (PType **type_p = &TypeHash[bucket]; *type_p != nullptr; type_p = &(*type_p)->HashNext)
 	{
 		PType *type = *type_p;
 		if (type == oldtype)
 		{
 			newtype->HashNext = type->HashNext;
-			type->HashNext = NULL;
+			type->HashNext = nullptr;
 			*type_p = newtype;
 			break;
 		}
@@ -3654,7 +3832,7 @@ void FTypeTable::AddType(PType *type, PClass *metatype, intptr_t parm1, intptr_t
 #ifdef _DEBUG
 	size_t bucketcheck;
 	assert(metatype == type->GetClass()->TypeTableType && "Metatype does not match passed object");
-	assert(FindType(metatype, parm1, parm2, &bucketcheck) == NULL && "Type must not be inserted more than once");
+	assert(FindType(metatype, parm1, parm2, &bucketcheck) == nullptr && "Type must not be inserted more than once");
 	assert(bucketcheck == bucket && "Passed bucket was wrong");
 #endif
 	type->HashNext = TypeHash[bucket];
@@ -3677,7 +3855,7 @@ void FTypeTable::AddType(PType *type)
 	metatype = type->GetClass()->TypeTableType;
 	type->GetTypeIDs(parm1, parm2);
 	bucket = Hash(metatype, parm1, parm2) % HASH_SIZE;
-	assert(FindType(metatype, parm1, parm2, NULL) == NULL && "Type must not be inserted more than once");
+	assert(FindType(metatype, parm1, parm2, nullptr) == nullptr && "Type must not be inserted more than once");
 
 	type->HashNext = TypeHash[bucket];
 	TypeHash[bucket] = type;
@@ -3732,7 +3910,7 @@ void FTypeTable::Mark()
 {
 	for (int i = HASH_SIZE - 1; i >= 0; --i)
 	{
-		if (TypeHash[i] != NULL)
+		if (TypeHash[i] != nullptr)
 		{
 			GC::Mark(TypeHash[i]);
 		}
@@ -3790,7 +3968,7 @@ PSymbol::~PSymbol()
 }
 
 PSymbolTable::PSymbolTable()
-: ParentSymbolTable(NULL)
+: ParentSymbolTable(nullptr)
 {
 }
 
@@ -3833,24 +4011,24 @@ void PSymbolTable::SetParentTable (PSymbolTable *parent)
 PSymbol *PSymbolTable::FindSymbol (FName symname, bool searchparents) const
 {
 	PSymbol * const *value = Symbols.CheckKey(symname);
-	if (value == NULL && searchparents && ParentSymbolTable != NULL)
+	if (value == nullptr && searchparents && ParentSymbolTable != nullptr)
 	{
 		return ParentSymbolTable->FindSymbol(symname, searchparents);
 	}
-	return value != NULL ? *value : NULL;
+	return value != nullptr ? *value : nullptr;
 }
 
 PSymbol *PSymbolTable::FindSymbolInTable(FName symname, PSymbolTable *&symtable)
 {
 	PSymbol * const *value = Symbols.CheckKey(symname);
-	if (value == NULL)
+	if (value == nullptr)
 	{
-		if (ParentSymbolTable != NULL)
+		if (ParentSymbolTable != nullptr)
 		{
 			return ParentSymbolTable->FindSymbolInTable(symname, symtable);
 		}
-		symtable = NULL;
+		symtable = nullptr;
-		return NULL;
+		return nullptr;
 	}
 	symtable = this;
 	return *value;
@@ -3859,9 +4037,9 @@ PSymbol *PSymbolTable::FindSymbolInTable(FName symname, PSymbolTable *&symtable)
 PSymbol *PSymbolTable::AddSymbol (PSymbol *sym)
 {
 	// Symbols that already exist are not inserted.
-	if (Symbols.CheckKey(sym->SymbolName) != NULL)
+	if (Symbols.CheckKey(sym->SymbolName) != nullptr)
 	{
-		return NULL;
+		return nullptr;
 	}
 	Symbols.Insert(sym->SymbolName, sym);
 	return sym;
@@ -3878,16 +4056,16 @@ PSymbol *PSymbolTable::ReplaceSymbol(PSymbol *newsym)
 {
 	// If a symbol with a matching name exists, take its place and return it.
 	PSymbol **symslot = Symbols.CheckKey(newsym->SymbolName);
-	if (symslot != NULL)
+	if (symslot != nullptr)
 	{
 		PSymbol *oldsym = *symslot;
 		*symslot = newsym;
 		return oldsym;
 	}
-	// Else, just insert normally and return NULL since there was no
+	// Else, just insert normally and return nullptr since there was no
 	// symbol to replace.
 	Symbols.Insert(newsym->SymbolName, newsym);
-	return NULL;
+	return nullptr;
 }
 
 IMPLEMENT_CLASS(PNamespace, false, true)
@@ -3969,7 +4147,7 @@ void RemoveUnusedSymbols()
 	// We do not need any non-field and non-function symbols in structs and classes anymore.
 	for (size_t i = 0; i < countof(TypeTable.TypeHash); ++i)
 	{
-		for (PType *ty = TypeTable.TypeHash[i]; ty != NULL; ty = ty->HashNext)
+		for (PType *ty = TypeTable.TypeHash[i]; ty != nullptr; ty = ty->HashNext)
 		{
 			if (ty->IsKindOf(RUNTIME_CLASS(PStruct)))
 			{

src/dobjtype.h

@@ -247,6 +247,7 @@ public:
 	// object is destroyed.
 	virtual void SetDefaultValue(void *base, unsigned offset, TArray<FTypeAndOffset> *special=NULL) const;
 	virtual void SetPointer(void *base, unsigned offset, TArray<size_t> *ptrofs = NULL) const;
+	virtual void SetPointerArray(void *base, unsigned offset, TArray<size_t> *ptrofs = NULL) const;
 
 	// Initialize the value, if needed (e.g. strings)
 	virtual void InitializeValue(void *addr, const void *def) const;
@@ -534,7 +535,7 @@ class PClassPointer : public PPointer
 	DECLARE_CLASS(PClassPointer, PPointer);
 	HAS_OBJECT_POINTERS;
 public:
-	PClassPointer(class PClass *restrict);
+	PClassPointer(class PClass *restrict = nullptr);
 
 	class PClass *ClassRestriction;
 
@@ -542,8 +543,6 @@ public:
 
 	virtual bool IsMatch(intptr_t id1, intptr_t id2) const;
 	virtual void GetTypeIDs(intptr_t &id1, intptr_t &id2) const;
-protected:
-	PClassPointer();
 };
 
 // Struct/class fields ------------------------------------------------------
@@ -657,6 +656,14 @@ public:
 
 	virtual bool IsMatch(intptr_t id1, intptr_t id2) const;
 	virtual void GetTypeIDs(intptr_t &id1, intptr_t &id2) const;
+
+	void WriteValue(FSerializer &ar, const char *key, const void *addr) const override;
+	bool ReadValue(FSerializer &ar, const char *key, void *addr) const override;
+	void SetDefaultValue(void *base, unsigned offset, TArray<FTypeAndOffset> *specials) const override;
+	void InitializeValue(void *addr, const void *def) const override;
+	void DestroyValue(void *addr) const override;
+	void SetPointerArray(void *base, unsigned offset, TArray<size_t> *ptrofs = NULL) const override;
+
 protected:
 	PDynArray();
 };
@@ -801,6 +808,7 @@ public:
 	PClass				*ParentClass;	// the class this class derives from
 	const size_t		*Pointers;		// object pointers defined by this class *only*
 	const size_t		*FlatPointers;	// object pointers defined by this class and all its superclasses; not initialized by default
+	const size_t		*ArrayPointers;	// dynamic arrays containing object pointers.
 	BYTE				*Defaults;
 	bool				 bRuntimeClass;	// class was defined at run-time, not compile-time
 	bool				 bExported;		// This type has been declared in a script
@@ -818,6 +826,7 @@ public:
 	PField *AddField(FName name, PType *type, DWORD flags=0) override;
 	void InitializeActorInfo();
 	void BuildFlatPointers();
+	void BuildArrayPointers();
 	void DestroySpecials(void *addr) const;
 	const PClass *NativeClass() const;
 

src/scripting/codegeneration/codegen.cpp

@@ -542,7 +542,7 @@ ExpEmit FxConstant::Emit(VMFunctionBuilder *build)
 		{
 			tag = ATAG_STATE;
 		}
-		else if (value.Type->GetLoadOp() == OP_LO)
+		else if (value.Type->GetLoadOp() != OP_LP)
 		{
 			tag = ATAG_OBJECT;
 		}
@@ -6356,7 +6356,7 @@ ExpEmit FxClassDefaults::Emit(VMFunctionBuilder *build)
 	ob.Free(build);
 	ExpEmit meta(build, REGT_POINTER);
 	build->Emit(OP_META, meta.RegNum, ob.RegNum);
-	build->Emit(OP_LO, meta.RegNum, meta.RegNum, build->GetConstantInt(myoffsetof(PClass, Defaults)));
+	build->Emit(OP_LOS, meta.RegNum, meta.RegNum, build->GetConstantInt(myoffsetof(PClass, Defaults)));
 	return meta;
 
 }
@@ -8874,7 +8874,7 @@ ExpEmit FxGetParentClass::Emit(VMFunctionBuilder *build)
 		op.Free(build);
 	}
 	ExpEmit to(build, REGT_POINTER);
-	build->Emit(OP_LO, to.RegNum, op.RegNum, build->GetConstantInt(myoffsetof(PClass, ParentClass)));
+	build->Emit(OP_LOS, to.RegNum, op.RegNum, build->GetConstantInt(myoffsetof(PClass, ParentClass)));
 	return to;
 }
 
@@ -8946,7 +8946,7 @@ ExpEmit FxGetDefaultByType::Emit(VMFunctionBuilder *build)
 		build->Emit(OP_LKP, to.RegNum, op.RegNum);
 		op = to;
 	}
-	build->Emit(OP_LO, to.RegNum, op.RegNum, build->GetConstantInt(myoffsetof(PClass, Defaults)));
+	build->Emit(OP_LOS, to.RegNum, op.RegNum, build->GetConstantInt(myoffsetof(PClass, Defaults)));
 	return to;
 }
 
@@ -10683,8 +10683,7 @@ ExpEmit FxLocalVariableDeclaration::Emit(VMFunctionBuilder *build)
 
 				case REGT_POINTER:
 				{
-					bool isobject = ValueType->IsKindOf(RUNTIME_CLASS(PClassPointer)) || (ValueType->IsKindOf(RUNTIME_CLASS(PPointer)) && static_cast<PPointer*>(ValueType)->PointedType->IsKindOf(RUNTIME_CLASS(PClass)));
+					build->Emit(OP_LKP, RegNum, build->GetConstantAddress(constval->GetValue().GetPointer(), ValueType->GetLoadOp() != OP_LP ? ATAG_OBJECT : ATAG_GENERIC));
-					build->Emit(OP_LKP, RegNum, build->GetConstantAddress(constval->GetValue().GetPointer(), isobject ? ATAG_OBJECT : ATAG_GENERIC));
 					break;
 				}
 				case REGT_STRING:
@@ -10824,7 +10823,7 @@ ExpEmit FxStaticArray::Emit(VMFunctionBuilder *build)
 	{
 		TArray<void*> cvalues;
 		for (auto v : values) cvalues.Push(static_cast<FxConstant *>(v)->GetValue().GetPointer());
-		StackOffset = build->AllocConstantsAddress(cvalues.Size(), &cvalues[0], ElementType->GetLoadOp() == OP_LO ? ATAG_OBJECT : ATAG_GENERIC);
+		StackOffset = build->AllocConstantsAddress(cvalues.Size(), &cvalues[0], ElementType->GetLoadOp() != OP_LP ? ATAG_OBJECT : ATAG_GENERIC);
 		break;
 	}
 	}

src/scripting/thingdef_data.cpp

@@ -1141,19 +1141,8 @@ DEFINE_ACTION_FUNCTION(FStringStruct, AppendFormat)
 DEFINE_ACTION_FUNCTION(FStringStruct, Mid)
 {
 	PARAM_SELF_STRUCT_PROLOGUE(FString);
-	PARAM_INT(ipos);
+	PARAM_UINT(pos);
-	PARAM_INT(ilen);
+	PARAM_UINT(len);
-	// validate. we don't want to crash if someone passes negative values.
-	// with size_t it's handled naturally I think, as it's unsigned, but not in ZScript.
-	if (ipos < 0) ipos = 0;
-	if (ilen < 0) ilen = 0;
-	// convert to size_t to prevent overflows here
-	size_t slen = self->Len();
-	size_t pos = (size_t)ipos;
-	size_t len = (size_t)ilen;
-	if (pos > slen) pos = slen - 1;
-	if (pos + len > slen)
-		len = slen - pos;
 	FString s = self->Mid(pos, len);
 	ACTION_RETURN_STRING(s);
 }
@@ -1161,7 +1150,7 @@ DEFINE_ACTION_FUNCTION(FStringStruct, Mid)
 DEFINE_ACTION_FUNCTION(FStringStruct, Len)
 {
 	PARAM_SELF_STRUCT_PROLOGUE(FString);
-	ACTION_RETURN_INT(self->Len());
+	ACTION_RETURN_INT((int)self->Len());
 }
 
 // CharAt and CharCodeAt is how JS does it, and JS is similar here in that it doesn't have char type as int.
@@ -1169,7 +1158,7 @@ DEFINE_ACTION_FUNCTION(FStringStruct, CharAt)
 {
 	PARAM_SELF_STRUCT_PROLOGUE(FString);
 	PARAM_INT(pos);
-	int slen = self->Len();
+	int slen = (int)self->Len();
 	if (pos < 0 || pos >= slen)
 		ACTION_RETURN_STRING("");
 	ACTION_RETURN_STRING(FString((*self)[pos]));
@@ -1179,7 +1168,7 @@ DEFINE_ACTION_FUNCTION(FStringStruct, CharCodeAt)
 {
 	PARAM_SELF_STRUCT_PROLOGUE(FString);
 	PARAM_INT(pos);
-	int slen = self->Len();
+	int slen = (int)self->Len();
 	if (pos < 0 || pos >= slen)
 		ACTION_RETURN_INT(0);
 	ACTION_RETURN_INT((*self)[pos]);

src/scripting/vm/vm.h

@@ -997,6 +997,7 @@ void NullParam(const char *varname);
 
 // For required parameters.
 #define PARAM_INT_AT(p,x)			assert((p) < numparam); assert(param[p].Type == REGT_INT); int x = param[p].i;
+#define PARAM_UINT_AT(p,x)			assert((p) < numparam); assert(param[p].Type == REGT_INT); unsigned x = param[p].i;
 #define PARAM_BOOL_AT(p,x)			assert((p) < numparam); assert(param[p].Type == REGT_INT); bool x = !!param[p].i;
 #define PARAM_NAME_AT(p,x)			assert((p) < numparam); assert(param[p].Type == REGT_INT); FName x = ENamedName(param[p].i);
 #define PARAM_SOUND_AT(p,x)			assert((p) < numparam); assert(param[p].Type == REGT_INT); FSoundID x = param[p].i;
@@ -1040,6 +1041,7 @@ void NullParam(const char *varname);
 #define PARAM_PROLOGUE				int paramnum = -1;
 
 #define PARAM_INT(x)				++paramnum; PARAM_INT_AT(paramnum,x)
+#define PARAM_UINT(x)				++paramnum; PARAM_UINT_AT(paramnum,x)
 #define PARAM_BOOL(x)				++paramnum; PARAM_BOOL_AT(paramnum,x)
 #define PARAM_NAME(x)				++paramnum; PARAM_NAME_AT(paramnum,x)
 #define PARAM_SOUND(x)				++paramnum; PARAM_SOUND_AT(paramnum,x)

src/scripting/vm/vmexec.h

@@ -347,6 +347,17 @@ begin:
 		GETADDR(PA,RC,X_WRITE_NIL);
 		*(void **)ptr = reg.a[B];
 		NEXTOP;
+	OP(SO):
+		ASSERTA(a); ASSERTA(B); ASSERTKD(C);
+		GETADDR(PA,KC,X_WRITE_NIL);
+		*(void **)ptr = reg.a[B];
+		GC::WriteBarrier((DObject*)*(void **)ptr);
+		NEXTOP;
+	OP(SO_R):
+		ASSERTA(a); ASSERTA(B); ASSERTD(C);
+		GETADDR(PA,RC,X_WRITE_NIL);
+		GC::WriteBarrier((DObject*)*(void **)ptr);
+		NEXTOP;
 	OP(SV2):
 		ASSERTA(a); ASSERTF(B+1); ASSERTKD(C);
 		GETADDR(PA,KC,X_WRITE_NIL);

src/scripting/vm/vmops.h

@@ -70,6 +70,8 @@ xx(SS,		ss,		RPRSKI,		SS_R,	4, REGT_INT),		// store string
 xx(SS_R,	ss,		RPRSRI,		NOP,	0, 0),
 xx(SP,		sp,		RPRPKI,		SP_R,	4, REGT_INT),		// store pointer
 xx(SP_R,	sp,		RPRPRI,		NOP,	0, 0),
+xx(SO,		sp,		RPRPKI,		SO_R,	4, REGT_INT),		// store object pointer with write barrier (only needed for non thinkers and non types
+xx(SO_R,	sp,		RPRPRI,		NOP,	0, 0),
 xx(SV2,		sv2,	RPRVKI,		SV2_R,	4, REGT_INT),		// store vector2
 xx(SV2_R,	sv2,	RPRVRI,		NOP,	0, 0),
 xx(SV3,		sv3,	RPRVKI,		SV3_R,	4, REGT_INT),		// store vector3