Taylor Blau <me@xxxxxxxxxxxx> writes: > On Sun, Dec 06, 2020 at 02:54:31AM +0000, Elijah Newren via GitGitGadget wrote: >> From: Elijah Newren <newren@xxxxxxxxx> >> >> diffcore-rename had two different checks of the form >> >> if ((a < limit || b < limit) && >> a * b <= limit * limit) >> >> Since these are all non-negative integers, this can be simplified to >> >> if (a * b <= limit * limit) > > Makes sense. I've always assumed that the original was for correctness (if a and b are both larger than limit, a*b could end up being smaller than limit*limit when the result of multiplication of the former wraps around but not the latter) ... >> The only advantage of the former would be in avoiding a couple >> multiplications in the rare case that both a and b are BOTH very large. >> I see no reason for such an optimization given that this code is not in >> any kind of loop. Prefer code simplicity here and change to the latter >> form. > > If you were really paranoid, you could perform these checks with > unsigned_mult_overflows(), but I don't think that it's worth doing so > here. ... and in no way as an optimization. So, I dunno.
