One embodiment disclosed relates to a method of compiling a program to be executed on a target central processing unit (CPU). The method includes opportunistically scheduling diagnostic testing of CPU registers. The method may include use of a predetermined level of aggressiveness for the scheduling of the register diagnostic testing. The scheduled diagnostic testing may include writing known data to a register, reading data from the register, and comparing the known data with the data that was read. If the comparison indicates a difference, then a jump may occur to a fault handler routine.