https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113481
--- Comment #6 from Georg-Johann Lay <gjl at gcc dot gnu.org> --- This is as simple as it gets: void Afun5 (__uint24 num) { __asm volatile ("" :: "r" (num)); } void func (void) { Afun5 (0xcccccc); }