Can compiler optimization introduce bugs?

Question

Today I had a discussion with a friend of mine and we debated for a couple of hours about \"compiler optimization\".

I defended the point that sometimes

Answer 1

Yes, compiler optimizations can be dangerous. Usually hard real-time software projects forbids optimizations for this very reason. Anyway, do you know of any software with no bugs?

Aggressive optimizations may cache or even do strange assumptions with your variables. The problem is not only with the stability of your code, but also they can fool your debugger. I have seen several times a debugger failing to represent the memory contents because some optimizations retained a variable value within the registers of the micro

The very same thing can happen to your code. The optimization puts a variable into a register and do not write to the variable until it has finished. Now imagine how different things can be if your code has pointers to variables in your stack and it has several threads