svn commit: r229415 - head/lib/libvgl
pfg at freebsd.org
Tue Jan 10 19:16:28 UTC 2012
--- Mar 10/1/12, John-Mark Gurney <jmg at funkthat.com> ha scritto:
> Eitan Adler wrote this message on
> Mon, Jan 09, 2012 at 23:48 -0500:
> > On Mon, Jan 9, 2012 at 11:02 PM, John-Mark Gurney
> <jmg at funkthat.com>
> > > Last time I did benchmarking on this ~10 years
> > > ago, it was slower to use xor instead of
> > > using assignments...
> > I'd be shocked if the compiler didn't optimize this
> > away to an XCHG.
> As someone else mentioned, it did... But it's still
> an obfuscation of the code...
> Not everyone knows this "trick" to swap two vars...
> If it isn't timing critical, it's better to be
The code was taken from a book and it's pretty much
ubiquitous as-is. If not everyone knows this "trick",
then I guess it simply proves that there is a lot of
value in reading books after all ;-).
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