The product of 'num' and 'num2' is always going to be a multiple of 'num', so there won't be any error introduced by flooring when dividing by 'num' again. One

The product of 'num' and 'num2' is always going to be a multiple of 'num', so there won't be any error introduced by flooring when dividing by 'num' again. One thing that can happen is an integer overflow: if you pass (0x10000, 0x10000), icc's and gcc's versions will calculate 0x10000 * 0x10000 = 0, 0 / 0x10000 = 0, while clang will return 0x10000. But clang's not wrong: signed integer overflow is undefined behavior in C, so compilers are allowed to just assume it never happens when making optimizations.