Date: Sat, 22 Mar 2003 10:28:46 -0800 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: David Schultz <das@FreeBSD.ORG> Cc: Till Riedel <till@f111.hadiko.de>, freebsd-current@FreeBSD.ORG Subject: Re: libm problem Message-ID: <20030322182846.GA81615@troutmask.apl.washington.edu> In-Reply-To: <20030322051443.GA13854@HAL9000.homeunix.com> References: <20030318173051.GA2322@f111.hadiko.de> <20030319131317.GA670@HAL9000.homeunix.com> <20030321235237.GA8097@f111.hadiko.de> <20030322111233.F4471@gamplex.bde.org> <20030322005435.GA8393@f111.hadiko.de> <20030322051443.GA13854@HAL9000.homeunix.com>
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On Fri, Mar 21, 2003 at 09:14:43PM -0800, David Schultz wrote:
> Thus spake Till Riedel <till@f111.hadiko.de>:
> > I now know the thing that makes it break.
> >
> > cc -O2 -pipe -mcpu=pentiumpro -c /usr/src/lib/msun/src/e_pow.c
> > works fine!
> > cc -O0 -pipe -march=pentium4 -c /usr/src/lib/msun/src/e_pow.c
> > ... works
> > but...
> > cc -O -pipe -march=pentium4 -c /usr/src/lib/msun/src/e_pow.c
> > breaks it. Hey its only gcc :-), nothing to worry about.
> > I think that 0 is nice number: so why don't optimize everithing to down it.
> > -O seems to minimize numbers not calculation time. Does anyone know the
> > flag to turn that off.
>
> If you have the time and inclination, I suggest reporting this
> problem to the gcc folks. For now, don't use Pentium 4
> optimizations. Not only are they apparently broken, they also
> generate slower code than you get by optimizing for a PPro, or
> even a 386.
>
Pentium 4 is definitely broken on 5.x. Perhaps, we should remove
the footshooting.
--- bsd.cpu.mk.orig Sat Mar 22 10:23:42 2003
+++ bsd.cpu.mk Sat Mar 22 10:27:11 2003
@@ -62,7 +62,9 @@
. elif ${CPUTYPE} == "k5"
_CPUCFLAGS = -march=pentium
. elif ${CPUTYPE} == "p4"
-_CPUCFLAGS = -march=pentium4
+# XXX gcc 3.2.2 appears to generate bad code on FreeBSD 5.x
+#_CPUCFLAGS = -march=pentium4
+_CPUCFLAGS = -march=pentiumpro
. elif ${CPUTYPE} == "p3"
_CPUCFLAGS = -march=pentium3
. elif ${CPUTYPE} == "p2"
--
Steve
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