Date: Tue, 23 Sep 2003 10:33:11 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: Peter Wemm <peter@FreeBSD.org> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/i386/include endian.h Message-ID: <Pine.NEB.3.96L.1030923103120.82831A-100000@fledge.watson.org> In-Reply-To: <200309222146.h8MLkmia045781@repoman.freebsd.org>
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On Mon, 22 Sep 2003, Peter Wemm wrote:
> Microoptimization to allow the compiler to evaluate ntohl() etc on
> known constants at compile time rather than at run time. We have a number
> of nasty hacks around the place to cache ntohl() of constants (eg: nfs).
> This change allows the compiler to compile-time evaluate ntohl(1) as
> 0x01000000 rather than having to emit assembler code to do it. This
> has other smaller flow-on effects because the compiler can see that
> ntohl(constant) itself has a constant value now and can propagate the
> compile time evaluation.
So should we now be doing a sweep through the tree to remove instances of
this? I.e.:
/*
* To avoid byte-swapping the same value over and over again.
*/
igmp_all_hosts_group = htonl(INADDR_ALLHOSTS_GROUP);
igmp_all_rtrs_group = htonl(INADDR_ALLRTRS_GROUP);
Etc?
Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org Network Associates Laboratories
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