Brian Budge <brian.budge@xxxxxxxxx> writes: >> It sounds like an idea which would be extremely expensive in compilation >> time. ÂNobody will use a compiler which takes too long to compile. >> >> We don't need to go as far as you suggest. ÂFor example, we could get >> better register allocation we if put more time into it, by trying out >> several different possibilities. ÂThat would be a fairly straightforward >> change, almost certainly easier to implement than what you suggest. ÂBut >> we don't do it, because it would take too long, so nobody would use it. >> >> You can casually say that nobody cares if the final compilation of >> firefox takes 1 CPU year, but in fact people do care, because they want >> to test what they ship. >> >> I don't want to discourage you from exploring this idea if you find it >> interesting, but I'm pretty skeptical that it would ever become part of >> a gcc distribution. >> > > On the other hand, I would put up with compile times that take twice > or even 10 times as long (for our final test and final release build) > for a 10% speedup of my code. If this is very easy to do, maybe it > makes sense to add an optimization flag that specifies how many > permutations are allowed to be checked? I wouldn't say it is very easy. I would just say that it is easier than a general solution solver. Ian
