Yes - as long as x is unsigned, then (x % 1024) will be compiled to the same thing as (x & 1023) with any reasonable compiler. If your hashtable dynamically re

Yes - as long as x is unsigned, then (x % 1024) will be compiled to the same thing as (x & 1023) with any reasonable compiler. If your hashtable dynamically resizes though, (x % size) will use a full divide. You could keep the log2 of the size around instead, and rely on (x % (1U << size_shift)) being optimised (this works on gcc: https://godbolt.org/z/HbGnJH https://godbolt.org/z/HbGnJH) but (x & (size - 1)) might be easier at that point.