- implemented pass-by-reference arguments - so far only for memory based variables.

- changed Dehacked weapon function lookup to check the symbol table instead of directly referencing the VM functions. Once scriptified these pointers will no longer be available.
- removed all special ATAGs from the VM. While well intentioned any pointer tagged with them is basically unusable because it'd trigger asserts all over the place.
- scriptified A_Punch for testing pass-by-reference parameters and stack variables.

src/scripting/codegeneration/codegen.cpp

@@ -3547,7 +3547,7 @@ ExpEmit FxShift::Emit(VMFunctionBuilder *build)
 	if (!op1.Konst)
 	{
 		op1.Free(build);
-		instr = InstrMap[index][op2.Konst? 0:2];
+		instr = InstrMap[index][op2.Konst? 2:0];
 	}
 	else
 	{
@@ -7067,7 +7067,8 @@ FxExpression *FxVMFunctionCall::Resolve(FCompileContext& ctx)
 	SAFE_RESOLVE_OPT(Self, ctx);
 	bool failed = false;
 	auto proto = Function->Variants[0].Proto;
-	auto argtypes = proto->ArgumentTypes;
+	auto &argtypes = proto->ArgumentTypes;
+	auto &argflags = Function->Variants[0].ArgFlags;
 
 	int implicit = Function->GetImplicitArgs();
 
@@ -7100,8 +7101,29 @@ FxExpression *FxVMFunctionCall::Resolve(FCompileContext& ctx)
 			}
 			assert(type != nullptr);
 
-			FxExpression *x = new FxTypeCast(ArgList[i], type, false);
-			x = x->Resolve(ctx);
+			FxExpression *x;
+			if (!(argflags[i + implicit] & VARF_Ref))
+			{
+				x = new FxTypeCast(ArgList[i], type, false);
+				x = x->Resolve(ctx);
+			}
+			else
+			{
+				bool writable;
+				ArgList[i] = ArgList[i]->Resolve(ctx);	// nust be resolved before the address is requested.
+				ArgList[i]->RequestAddress(ctx, &writable);
+				ArgList[i]->ValueType = NewPointer(ArgList[i]->ValueType);
+				// For a reference argument the types must match 100%.
+				if (type != ArgList[i]->ValueType)
+				{
+					ScriptPosition.Message(MSG_ERROR, "Type mismatch in reference argument", Function->SymbolName.GetChars());
+					x = nullptr;
+				}
+				else
+				{
+					x = ArgList[i];
+				}
+			}
 			failed |= (x == nullptr);
 			ArgList[i] = x;
 		}

src/scripting/thingdef.cpp

@@ -131,7 +131,7 @@ void SetImplicitArgs(TArray<PType *> *args, TArray<DWORD> *argflags, TArray<FNam
 			{
 				args->Push(NewPointer(cls));
 			}
-			args->Push(TypeState/*Info*/);	// fixme: TypeState is not the correct type here!!!
+			args->Push(NewPointer(NewStruct("FStateParamInfo", nullptr)));
 		}
 		if (argflags != nullptr)
 		{

src/scripting/thingdef_data.cpp

@@ -388,7 +388,7 @@ static FFlagDef InventoryFlagDefs[] =
 	DEFINE_DEPRECATED_FLAG(INTERHUBSTRIP),
 };
 
-static FFlagDef WeaponFlagDefs[] =
+FFlagDef WeaponFlagDefs[] =
 {
 	// Weapon flags
 	DEFINE_FLAG(WIF, NOAUTOFIRE, AWeapon, WeaponFlags),
@@ -411,12 +411,14 @@ static FFlagDef WeaponFlagDefs[] =
 	DEFINE_FLAG(WIF, NOAUTOAIM, AWeapon, WeaponFlags),
 	DEFINE_FLAG(WIF, NODEATHDESELECT, AWeapon, WeaponFlags),
 	DEFINE_FLAG(WIF, NODEATHINPUT, AWeapon, WeaponFlags),
-	
-	DEFINE_DUMMY_FLAG(NOLMS, false),
 	DEFINE_FLAG(WIF, ALT_USES_BOTH, AWeapon, WeaponFlags),
+
+	DEFINE_DUMMY_FLAG(NOLMS, false),
 	DEFINE_DUMMY_FLAG(ALLOW_WITH_RESPAWN_INVUL, false),
 };
 
+
+
 static FFlagDef PlayerPawnFlagDefs[] =
 {
 	// PlayerPawn flags

src/scripting/vm/vm.h

@@ -157,13 +157,15 @@ enum
 	ATAG_OBJECT,			// pointer to an object; will be followed by GC
 
 	// The following are all for documentation during debugging and are
-	// functionally no different than ATAG_GENERIC.
+	// functionally no different than ATAG_GENERIC (meaning they are useless because they trigger asserts all over the place.)
 
+	/*
 	ATAG_FRAMEPOINTER,		// pointer to extra stack frame space for this function
 	ATAG_DREGISTER,			// pointer to a data register
 	ATAG_FREGISTER,			// pointer to a float register
 	ATAG_SREGISTER,			// pointer to a string register
 	ATAG_AREGISTER,			// pointer to an address register
+	*/
 
 	ATAG_RNG,				// pointer to FRandom
 	ATAG_STATE  = ATAG_GENERIC,			// pointer to FState (cannot have its own type because there's no means to track inside the VM.)

src/scripting/vm/vmexec.h

@@ -87,7 +87,7 @@ begin:
 	OP(LFP):
 		ASSERTA(a); assert(sfunc != NULL); assert(sfunc->ExtraSpace > 0);
 		reg.a[a] = f->GetExtra();
-		reg.atag[a] = ATAG_FRAMEPOINTER;
+		reg.atag[a] = ATAG_GENERIC;	// using ATAG_FRAMEPOINTER will cause endless asserts.
 		NEXTOP;
 
 	OP(LB):
@@ -461,7 +461,7 @@ begin:
 					break;
 				case REGT_INT | REGT_ADDROF:
 					assert(C < f->NumRegD);
-					::new(param) VMValue(&reg.d[C], ATAG_DREGISTER);
+					::new(param) VMValue(&reg.d[C], ATAG_GENERIC);
 					break;
 				case REGT_INT | REGT_KONST:
 					assert(C < sfunc->NumKonstD);
@@ -473,7 +473,7 @@ begin:
 					break;
 				case REGT_STRING | REGT_ADDROF:
 					assert(C < f->NumRegS);
-					::new(param) VMValue(&reg.s[C], ATAG_SREGISTER);
+					::new(param) VMValue(&reg.s[C], ATAG_GENERIC);
 					break;
 				case REGT_STRING | REGT_KONST:
 					assert(C < sfunc->NumKonstS);
@@ -485,7 +485,7 @@ begin:
 					break;
 				case REGT_POINTER | REGT_ADDROF:
 					assert(C < f->NumRegA);
-					::new(param) VMValue(&reg.a[C], ATAG_AREGISTER);
+					::new(param) VMValue(&reg.a[C], ATAG_GENERIC);
 					break;
 				case REGT_POINTER | REGT_KONST:
 					assert(C < sfunc->NumKonstA);
@@ -512,7 +512,7 @@ begin:
 					break;
 				case REGT_FLOAT | REGT_ADDROF:
 					assert(C < f->NumRegF);
-					::new(param) VMValue(&reg.f[C], ATAG_FREGISTER);
+					::new(param) VMValue(&reg.f[C], ATAG_GENERIC);
 					break;
 				case REGT_FLOAT | REGT_KONST:
 					assert(C < sfunc->NumKonstF);

src/scripting/zscript/zcc_compile.cpp

@@ -2160,6 +2160,7 @@ void ZCCCompiler::InitFunctions()
 								if ((flags & VARF_Out) || (type != TypeVector2 && type != TypeVector3))
 								{
 									type = NewPointer(type);
+									flags |= VARF_Ref;
 								}
 								else if (type == TypeVector2)
 								{