Restore "direct" call optimization for DECORATE

src/thingdef/thingdef.cpp

@@ -277,7 +277,7 @@ static void FinishThingdef()
 
 		// Can we call this function directly without wrapping it in an
 		// anonymous function? e.g. Are we passing any parameters to it?
-		func = NULL;//tcall->Code->GetDirectFunction();
+		func = tcall->Code->GetDirectFunction();
 		if (func == NULL)
 		{
 			FCompileContext ctx(tcall->ActorClass);

src/thingdef/thingdef_exp.h

@@ -835,9 +835,9 @@ public:
 	FxExpression *Resolve(FCompileContext&);
 	ExpEmit Emit(VMFunctionBuilder *build);
 	ExpEmit Emit(VMFunctionBuilder *build, bool tailcall);
-	unsigned GetArgCount() { return ArgList == NULL ? 0 : ArgList->Size(); }
+	unsigned GetArgCount() const { return ArgList == NULL ? 0 : ArgList->Size(); }
-	VMFunction *GetVMFunction() { return Function->Variants[0].Implementation; }
+	VMFunction *GetVMFunction() const { return Function->Variants[0].Implementation; }
-	VMFunction *GetDirectFunction();
+	bool IsDirectFunction();
 };
 
 //==========================================================================
@@ -891,6 +891,7 @@ public:
 	FxReturnStatement(FxVMFunctionCall *call, const FScriptPosition &pos);
 	FxExpression *Resolve(FCompileContext&);
 	ExpEmit Emit(VMFunctionBuilder *build);
+	VMFunction *GetDirectFunction();
 };
 
 //==========================================================================

src/thingdef/thingdef_expression.cpp

@@ -3202,24 +3202,6 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build, bool tailcall)
 	}
 }
 
-//==========================================================================
-//
-// FxVMFunctionCall :: GetDirectFunction
-//
-// If the function is not passed any explicit arguments, returns the
-// function. Otherwise returns NULL.
-//
-//==========================================================================
-
-VMFunction *FxVMFunctionCall::GetDirectFunction()
-{
-	if (GetArgCount() == 0)
-	{
-		return GetVMFunction();
-	}
-	return NULL;
-}
-
 //==========================================================================
 //
 //
@@ -3505,6 +3487,19 @@ ExpEmit FxReturnStatement::Emit(VMFunctionBuilder *build)
 	return ExpEmit();
 }
 
+VMFunction *FxReturnStatement::GetDirectFunction()
+{
+	// If this return statement calls a function with no arguments,
+	// then it can be a "direct" function. That is, the DECORATE
+	// definition can call that function directly without wrapping
+	// it inside VM code.
+	if (Call != NULL && Call->GetArgCount() == 0)
+	{
+		return Call->GetVMFunction();
+	}
+	return NULL;
+}
+
 //==========================================================================
 //
 //==========================================================================