Date: Mon, 5 Jul 2004 12:48:29 -0700 From: "David O'Brien" <obrien@FreeBSD.ORG> To: Kris Kennaway <kris@obsecurity.org> Cc: Dag-Erling Smorgrav <des@FreeBSD.ORG> Subject: Re: cvs commit: src/share/examples/etc make.conf Message-ID: <20040705194829.GA3743@dragon.nuxi.com> In-Reply-To: <20040704232050.GA90994@xor.obsecurity.org> References: <200407030941.i639fwt8078389@repoman.freebsd.org> <20040704032139.GA93138@VARK.homeunix.com> <20040704051607.GA78676@xor.obsecurity.org> <20040704205648.GA1617@dragon.nuxi.com> <20040704232050.GA90994@xor.obsecurity.org>
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On Sun, Jul 04, 2004 at 04:20:50PM -0700, Kris Kennaway wrote: > On Sun, Jul 04, 2004 at 01:56:48PM -0700, David O'Brien wrote: > > On Sat, Jul 03, 2004 at 10:16:07PM -0700, Kris Kennaway wrote: > > > On Sat, Jul 03, 2004 at 08:21:39PM -0700, David Schultz wrote: > > > > FWIW, I've been compiling most things with -O2 for a while (to > > > > find -O2 bugs, not for speed) and haven't noticed many problems. > > > > The only significant one I know of is that -O2 breaks > > > > floating-point exceptions in libm because gcc doesn't support the > > > > FENV_ACCESS pragma. I think for some routines like rint(3), it > > > > may even give the wrong answer due to incorrect optimizations, but > > > > I'd have to check that again. > > > > > > > > AFAIK, the necessary functionality to make gcc's optimizer treat > > > > floating-point code in a sane manner isn't on the horizon, so > > > > maybe -O2 should be automatically turned off while compiling libm > > > > (and perhaps libalias as well). That would make it more > > > > easily justifiable to make -O2 the default at some future point. > > > > > > I don't think we can ever make it the default since there's likely to > > > be a lot of software in ports that would be broken too. > > > > 99% of the ports that "may break" build with -O2 on Linux (as -O2 is > > their default). What is different about us vs. Linux for these ports? > > We care about not introducing instability into our packages? > > If we have >=2 -O2 bugs in our source tree alone, why should you think > that none of the 11000 ports are affected? Because most everything in the ports collection was developed on Linux using -O2. The bugs are in our code, not gcc's -O2. -- -- David (obrien@FreeBSD.org)
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