Superdeformed states in light N=Z nuclei are studied by means of the self-consistent cranking calculation (i.e., the P+QQ model based on the cranked Hartree-Fock-Bogoliubov method). Analyses are given for two typical cases of superdeformed bands in the A similar or equal to 40 mass region, that is, bands where backbending is absent (Ca-40) or present (Ar-36). Investigations are carried out particularly for the following points: cross-shell excitations in the sd and pf shells; the role of the g(9/2) and d(5/2) orbitals; the effect of nuclear pairing; and the interplay between triaxiality and band termination.