Date: Tue, 30 Sep 2003 23:16:39 -0700 From: David Schultz <das@FreeBSD.ORG> To: Maxime Henrion <mux@FreeBSD.ORG> Cc: cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/sys cdefs.h Message-ID: <20031001061639.GA19012@VARK.homeunix.com> In-Reply-To: <200309302045.h8UKjE9j021972@repoman.freebsd.org> References: <200309302045.h8UKjE9j021972@repoman.freebsd.org>
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On Tue, Sep 30, 2003, Maxime Henrion wrote: > mux 2003/09/30 13:45:14 PDT > > FreeBSD src repository > > Modified files: > sys/sys cdefs.h > Log: > Introduce new __predict_false(exp) and __predict_true(exp) keywords. > Their purpose is to give explicit hints to the compiler to judge > the likelyhood of a test to succeed or fail. Not all architectures > have support for such optimizations, but for those who do, it can > give a nice performance improvement in hot loops. > > Obviously, this should be used very rarely in very specific code. > > Reviewed by: peter > Obtained from: OpenBSD Cool, I'm glad we finally have these. (FWIW, I believe the macros originated with NetBSD.) Hopefully they will be used with reservation.
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