Your mistake is in assuming that the language C and its standard library are somehow defined in terms of some hardware, and that there somehow is a mapping betw

Your mistake is in assuming that the language C and its standard library are somehow defined in terms of some hardware, and that there somehow is a mapping between C functions and operators and CPU instructions - there isn't. The standard specifies for what input values an operation is defined and which conditions have to be met by the result, nowhere does it say how an implementation is supposed to compute the result, that's for the compiler to decide - as far as the standard is concerned, the compiler may compile all arithmetic to only ANDs and NOTs, though most practical compilers tend to try and choose instructions that give the best performance for a given computation, or just compute the result at compile time where possible.