Date: Tue, 12 Jun 2007 23:37:49 -0700 From: "Kip Macy" <kip.macy@gmail.com> To: "Bruce Evans" <bde@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/libkern mcount.c Message-ID: <b1fa29170706122337y558ca741k273e4babb78c936d@mail.gmail.com> In-Reply-To: <200706130617.l5D6HncF038605@repoman.freebsd.org> References: <200706130617.l5D6HncF038605@repoman.freebsd.org>
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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
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