A method for generating production code from a block diagram on a host computer is provided. A block in the block diagram has a number of input ports for receiving signals and a number of output ports for sending signals. The processor identifies a first block in the block diagram. The input signal is traced back to a second block upstream of the first block. Compliance with a optimization condition is checked, the optimization condition being fulfilled when a group of adjacent blocks has an assignment operation that affects one or more elements of the input signal while leaving at least one element of the composite variable unchanged. A combined production code is generated for the group of adjacent blocks when the optimization condition is fulfilled so that the combined production code includes write instructions for those elements of the composite variable that are affected by the assignment operation.