Date: Wed, 21 May 2003 18:10:14 -0700 From: "David O'Brien" <obrien@FreeBSD.ORG> To: Jon Lido <jlido@goof.com> Cc: freebsd-current@FreeBSD.ORG Subject: Re: gcc/libm floating-point bug? Message-ID: <20030522011014.GC27806@dragon.nuxi.com> In-Reply-To: <200305201512.27174.jlido@goof.com> References: <200305201025.30296.jlido@goof.com> <200305201216.10964.jlido@goof.com> <20030520180004.GA2372@HAL9000.homeunix.com> <200305201512.27174.jlido@goof.com>
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On Tue, May 20, 2003 at 03:12:27PM -0400, Jon Lido wrote: > On Tuesday 20 May 2003 02:00 pm, David Schultz wrote: > > On Tue, May 20, 2003, Jon Lido wrote: > > > Well, I do have a P4, and had built everything with -march=pentium4. > > > However, rebuilding the kernel and modules with -march=pentium3 produces > > > the same results. > > > > This isn't a kernel problem, so you need to rebuild libm and libc > > without -march=pentium4. You really don't want to be using the > > Pentium 4 optimizations in gcc 3.2 anyway; the generated code is > > generally slower. gcc 3.3 has fixes for a number of the bugs, but > > I don't know about the performance problems. > > Yes, this was the problem. I rebuilt world with -march=pentium3 and that did > the trick. Honest question of you -- I'll assume you're subscribed to freebsd-current@. How have you missed all the warnings from myself and others not to trust the -march=pentium4 optimizations? I honestly want to know so we can figure out a better way of getting the word out. > I'm not sure how CPUTYPE gets handled, but perhaps p4 should expand to > -march=pentium3, if possible. I feel some will screem if we take away the ability to use -march=pentium4 in places they know for sure will work. Unix is about mechanisms, not policy.
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