True, only executions of a program that exhibit undefined behavior are affected. But the moment it is clear a program will exhibit undefined behavior, the compi

True, only executions of a program that exhibit undefined behavior are affected. But the moment it is clear a program will exhibit undefined behavior, the compiler is already allowed to do whatever it wants. So if 20 lines below an important function call you will certainly call a function that will certainly cause undefined behavior, the important function call can be already be left out.