Is there some meaningful statistical data to justify keeping signed integer arithmetic overflow undefined?

Question

The C Standard explicitly specifies signed integer overflow as having undefined behavior. Yet most CPUs implement signed arithmetics with defined semantics

Answer 1

Not quite an example of optimization, but one useful consequence of undefined behaviour is -ftrapv command line switch of GCC/clang. It inserts code which crashes your program on integer overflow.

It won't work on unsigned integers, in accordance with the idea that unsigned overflow is intentional.

The Standard's wording on signed integer overflow ensures that people won't write overflowing code on purpose, so ftrapv is a useful tool to discover unintentional overflow.