Signed overflow optimization hazards in the kernel

Signed overflow optimization hazards in the kernel

The result of ... converting an integer to a signed integer type when the value cannot be represented in an object of that type ...

For conversion to a type of width N, the value is reduced modulo 2^N to be within range of the type;

I must be reading that wrongly, because that's not at all what GCC does. With -m32, int is a signed integer type of width 32. UINT_MAX reduced modulo 2^32 is UINT_MAX, which is not within the range of int. So this does not describe what (int)UINT_MAX does.

Rather, what GCC does appears to be the opposite of what the standard requires for conversion from negative number to unsigned integer (add UINT_MAX+1 until it fits): it subtracts UINT_MAX+1 until the value is within the range of int (in this case -1).