&gt; If on x86 INT_MAX+1==INT_MIN [...]<p>There is no such thing as &quot;+ on x86&quot;. &quot;+&quot; is an operator of the C language. Modern x86 has about two dozen instructions that can be used to perform additions, each with slightly different behaviour, and with different performance characteristics. Someone has to define how C&#x27;s &quot;+&quot; maps to those instructions. That is what the C standard does. The way it does that is by specifying properties that any implementation of C&#x27;s &quot;+&quot; needs to have, leaving the specific choice of instructions to the compiler writer.