On Wed, Apr 11, 2018 at 03:10:16PM +0100, David Howells wrote: > Colin Ian King <colin.k...@canonical.com> wrote: > > > >> - mask = (1 << nr_slots) - 1; > > >> + mask = (1ULL << nr_slots) - 1; > > > > > > nr_slots cannot be larger than 9, so what I wrote is actually fine and is > > > more efficient on a 32-bit machine. > > > > ok, sorry about the noise. > > It would be possible to cast the value to u64 before assigning it, I suppose. > Would that help? E.g.: > > mask = (u64)((1 << nr_slots) - 1); > > It looks a bit odd, though, since the cast is made implicitly anyway.
My feeling is that makes it worse. It would introduce a secret, unpublished static checker warning on my build and it doesn't help me as a reviewer. Ideally static analyzers should know that nr_slots is 0-9, but right now that seems pretty tricky to figure out... regards, dan carpenter
