The operation + on integer types maps to a built in method which performs addition with overflow checks. At the assembly level this looks like an "add" followed

The operation + on integer types maps to a built in method which performs addition with overflow checks. At the assembly level this looks like an "add" followed by a "jo" (jump on overflow set) to an undefined exception such as UD2. If you want wraparound addition you can use +& which removes the overflow check.