Messages in this thread | | | Date | Tue, 29 Feb 2000 08:19:15 +0000 | From | Ben Kosse <> | Subject | RE: Kernel bugs found using inspect tool |
| |
> nathan.zook@amd.com wrote: > > > if((a == b) | (c == d) | (e < f)) > > > > I'm right when I say "The rules have changed. Consider bit-logicals. Time > > your critical inner loops". It all depends on the exact details of the code > > & the processor. When c, d, e, and f are simple variables and the first two > > branches are hard to predict, bit-ors should be faster on all the latest > > superscalar systems. > If c, d, e and f are simple variables, then the compiler should be able to > tell that it makes no difference whatsoever whether | or || is used, and > should generate the same (fastest) code for both.
Not necessarily true. || has the side effect of allowing you to jump out after the first comparison. | *REQUIRES* you do all comparisons.
-- Ben Kosse <bkosse@iname.com>
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |