From owner-cvs-src@FreeBSD.ORG  Wed Jun 13 06:37:57 2007
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Date: Tue, 12 Jun 2007 23:37:49 -0700
From: "Kip Macy" <kip.macy@gmail.com>
To: "Bruce Evans" <bde@freebsd.org>
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Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org
Subject: Re: cvs commit: src/sys/libkern mcount.c
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On 6/12/07, Bruce Evans <bde@freebsd.org> wrote:
> bde         2007-06-13 06:17:48 UTC
>
>   FreeBSD src repository
>
>   Modified files:
>     sys/libkern          mcount.c
>   Log:
>   Unbreak high resolution profiling a little: use dummy asms to prevent
>   timing loops being optimized away.
>
>   Once apon a time, gcc promised not to optimize away timing loops, but
>   gcc started optimizing away the call to a null function in the timing
>   loop here some time between gcc-3.3.3 and gcc-3.4.6, and it started
>   optimizing away the timing loop itself some time between gcc-3.4.6
>   and gcc-4.2.


Will this fix the hang on boot that I saw earlier today?

-Kip