Date: Tue, 20 May 2003 11:03:36 -0700 From: David Schultz <das@FreeBSD.ORG> To: Terry Lambert <tlambert2@mindspring.com> Cc: freebsd-current@FreeBSD.ORG Subject: Re: gcc/libm floating-point bug? Message-ID: <20030520180336.GB2372@HAL9000.homeunix.com> In-Reply-To: <3ECA526F.A6E4A085@mindspring.com> References: <200305201025.30296.jlido@goof.com> <3ECA526F.A6E4A085@mindspring.com>
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On Tue, May 20, 2003, Terry Lambert wrote: > Jon Lido wrote: > > I've been running 5-CURRENT on my laptop for about a week now. I believe I > > may have found a bug in FreeBSD's gcc floating-point code generation, or > > perhaps more likely, in the math library. > [ ... ] > > I know my floating point hardware is fine, since I used to run xmms and artsd > > fine under Linux before I switched the machine to FreeBSD. > > > > I'd appreciate any help with further isolating and reproducing the bug. Has > > anyone else experienced this problem? > > There was a recent discussion about -mieee being set by > default in one of the Makefiles, which leaked into the > main code base. It may be that you need the option, or > you need to disable it (depending on when you downloaded > you copy of -current). That's for an Alpha-specific problem. The i386-specific problem is due to a bug gcc has that involves Pentium 4 code generation and aliasing. The latter can be fixed by removing -march=pentium4, disabling optimization, or upgrading to gcc 3.3. The former is intentional and not expected to change; gcc generates non-standard FP math code on Alpha because it saves a few instructions to deal with NaNs, etc. We work around it by setting -mieee in bsd.cpu.mk for Alpha.
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