1. A method of generating computer program instructions with a computer, comprising: analyzing components in a simulatable block diagram model with the computer to identify components that are critical to control of a hardware device and to identify components that are not critical to control of the hardware device; marking with the computer the components identified as critical to control of the hardware device as critical components; marking with the computer the components identified as not critical to control of the hardware device as non-critical components; generating the computer program instructions for the simulatable block diagram model with an automatic code generator on the computer, the computer program instructions implementing behavior of the block diagram model, said generating comprising; generating computer program instructions for the components of the block diagram model that are marked as critical; and ignoring the components of the block diagram model that are marked non-critical so that no computer program instructors are generated for the components of the block diagram model that are marked as non-critical.