sure. ubsan needs to be in the CI. only then you can try to upgrade to -O3 and -flto. even -fstrict-aliasing is then possible but in my cases I do even have cb

sure. ubsan needs to be in the CI. only then you can try to upgrade to -O3 and -flto. even -fstrict-aliasing is then possible but in my cases I do even have cbmc in my CI, formal verification. not just a single value is checked, all possible values are. overflows don't just happen with your simple test cases.