On Wed, 1 November 2006 15:52:09 -0500, Phillip Susi wrote: > > In other words, the only time this micro optimization will be of benefit > is if you are erroring out most of the time rather than only under > exceptional conditions, AND the error label isn't too far away for a > conditional branch to reach. In other words, just don't do it ;) The difference was in code size, so the icache impact would have benefitted the good case as well. "was" and "would have" because I finally got off my lazy arse and tested the code. With gcc 4.12 both variants compiled to exactly the same code. With 2.95 there was a one instruction (2 bytes) difference. I didn't test all the versions in between, but the advantage is definitely a thing of the past. And even if the 2 byte difference still existed, it wouldn't really matter much, we all agree on that. That's why I said: > >Both methods definitely work. Whether one is preferrable over the > >other is imo 90% taste and maybe 10% better code on some architecture. > >So just pick what you prefer. The only thing I was arguing was that one method would not work - it does. So I hope this was sufficient distraction for everyone and we can get back to work. :) Jörn -- You can't tell where a program is going to spend its time. Bottlenecks occur in surprising places, so don't try to second guess and put in a speed hack until you've proven that's where the bottleneck is. -- Rob Pike - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
