Date: Wed, 13 Jun 2007 18:47:58 +1000 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Kip Macy <kip.macy@gmail.com> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, Bruce Evans <bde@FreeBSD.org>, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/libkern mcount.c Message-ID: <20070613184656.N25269@delplex.bde.org> In-Reply-To: <b1fa29170706122337y558ca741k273e4babb78c936d@mail.gmail.com> References: <200706130617.l5D6HncF038605@repoman.freebsd.org> <b1fa29170706122337y558ca741k273e4babb78c936d@mail.gmail.com>
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On Tue, 12 Jun 2007, Kip Macy wrote: > 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? No. It's unlikely that you even configure profiling. Bruce
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