Beside optimization (as others have pointed out), disallowing wrapping of signed values has the important safety benefit that it permits run-time (and compile-t

Beside optimization (as others have pointed out), disallowing wrapping of signed values has the important safety benefit that it permits run-time (and compile-time) detection of arithmetic overflow (e.g. via -fsanitize=signed-integer-overflow). If signed arithmetic were defined to wrap, you could not enable such checks without potentially breaking existing correct code.