I had very bad experience of -O flag especially in case of ISRs. I don't use any optimisation levels... even at -O0 GCC seems to do something. Good practice as

I had very bad experience of -O flag especially in case of ISRs. I don't use any optimisation levels... even at -O0 GCC seems to do something. Good practice as per my experience is to check MCDC and code coverage at unit test level