And of course the code is wrong, because the behaviour is undefined - in 64-bit architectures it is very common to use 64-bit registers for `int` even if in mem

And of course the code is wrong, because the behaviour is undefined - in 64-bit architectures it is very common to use 64-bit registers for `int` even if in memory `sizeof(int) == 4`; thus `int a = INT_MAX;`, `a + 100` could still be greater than `INT_MAX`.