Comment by wren6991

You still have the overhead of a function call. If you just use / % operators then you'll get a call inserted to the libgcc or compiler-rt routine if you don't have the M extension, and those routines are div or mod only. Using stdlib for integer division seems like an odd choice.

If stdlib div() were promoted to a builtin one day (it currently is not in GCC afaict), and its implementation were inlined, then the compiler would recognise the common case of one side of the struct being dead, and you'd still end up with a single div/rem instruction.