Does that end up moving high bits into the low bits? That could possibly be very helpful for all sets of strings, since the equality test will start with the first byte, so it could better to have the rotr on the hash so that the hash is less affected by the first byte (and more affected by later bytes). Just hypothetically speaking that is where the implication could break down, since it doesn’t consider the non-uniform cost of the equality.
I didn’t look at their implementation, but in general, strings don’t have to be aligned so you can only peek one byte at a time looking for the end, besides not wanting to annoy valgrind and other similar UB detection tools by reading past the end of the string.
Strawman; nul-terminated strings are horribly slow for nearly every application. Hence I assume (especially given that they are using c++) that they are using length-accompanied strings rather than nul-terminated ones.
