> I'm not sure the price is so high. I googled around and came across > http://mdfs.net/Docs/Comp/ARM/Cookbook/cook3 (section 3.3). Dividing by > 2^n, (2^n + 2^m) or (2^n - 2^m) can be done using a small series of adds > and subtractions (important on ARM as it had no divide instruction at > the time). Most structures are going to be of one of these sizes ... > and in particular, struct page is 56 bytes in my config, which is 64 - 8. > Maybe sparse needs to be taught that dividing by 2^n [+-] 2^m is cheap > enough to not warn about. Usually you can just use x/n = x*(1/n) and generate *(1/n) with 1/n being computed at compile time. Multiplications are fast in hardware. gcc only does that when -Os is not set though (friends don't let friends compile with -Os...) -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
