The issue for me with posts like this is that it misses the issue.

Unaligned pointer accesses are UB because different systems handle it differently. This 'should' be to allow the program to be portable by doing what the system normally does.

Instead it's been highjacked by compiler writers, with the logic that "X is UB, therefore can't happen, therefore can be optimised away."

Int c = abs(a) + abs(b); If (a > c) //overflow

Is UB because some system might do overflow differently. In practice every system wraps around.

That should be a valid check, instead it gets optimised away because it 'can't' happen.

C gives you enough rope to hang yourself. The compiler writers don't trust you to use the rope properly.