Date: Tue, 21 Oct 2014 08:54:35 +0100 From: David Chisnall <theraven@FreeBSD.org> To: Andriy Gapon <avg@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org, "Alexander V. Chernikov" <melifaro@FreeBSD.org> Subject: Re: svn commit: r273274 - head/sys/netpfil/ipfw Message-ID: <6FEB1269-2A8D-48A7-A18E-2EAB9961EDA6@FreeBSD.org> In-Reply-To: <5443A83F.5090807@FreeBSD.org> References: <201410191115.s9JBFJxA058370@svn.freebsd.org> <5443A83F.5090807@FreeBSD.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 19 Oct 2014, at 13:02, Andriy Gapon <avg@FreeBSD.org> wrote: > I think that on platforms where an optimized version of fls() is = available that > would work faster than this cool piece of bit magic. If you're lucky, the compiler's idiom recogniser will spot this. You're = generally better off using the builtins though, because then the = compiler will expand them to something sensible (hopefully - old = versions of gcc did horribly inefficient things for bswap and clz on = platforms without native support). David
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?6FEB1269-2A8D-48A7-A18E-2EAB9961EDA6>