Undefined behaviour is undefined behaviour whatever optimisation level you use.
Some -f flags may extend the C standard and remove undefined behaviour in some cases (e.g. strict aliasing, signed integer overflow, writable string constants, etc.)
Undefined behaviour is undefined behaviour whatever optimisation level you use.
Some -f flags may extend the C standard and remove undefined behaviour in some cases (e.g. strict aliasing, signed integer overflow, writable string constants, etc.)