Gentoo Archives: gentoo-amd64

From: Mark Knecht <markknecht@×××××.com>
To: gentoo-amd64@l.g.o
Subject: Re: [gentoo-amd64] Possible Math Problem - Request For Verification [Solved]
Date: Sun, 26 Jun 2011 03:55:23
In Reply to: Re: [gentoo-amd64] Possible Math Problem - Request For Verification [Solved] by Frank Peters
On Sat, Jun 25, 2011 at 8:44 PM, Frank Peters <frank.peters@×××××××.net> wrote:
> On Sat, 25 Jun 2011 13:41:11 -0400 > Frank Peters <frank.peters@×××××××.net> wrote: > >> >> /tmp/fp-test-results/clib_DP.output: ucbtest UCBFAIL in cabsd at line 701 for double >> > > The culprit seems to be GCC optimization.  If I run the test with either "-O0" > or "-O1" flags I can eliminate the cabsd failure.  Using "-O2" or "-O3" will > result in the cabsd error. > > However, I've used "-O2" previously and had no problems with this test.  Possibly, > some of these new LTO and GRAPHITE capabilities of GCC are to blame, even though > I do not compile the ucbtest with either LTO or GRAPHITE enabled.  But GCC has itself > been compiled using LTO and GRAPHITE. > > Anyway, thanks for all who actually ran the test on their machines.  I was > thinking of filing bug reports with GLIBC and GCC and that would have turned > out to be foolish.  I did check the Changelogs for GLIBC and there doesn't seem > to have been any modification of the cabs() code over the last several versions. > > Frank Peters
I'm using -O2 here on all my machines. Certainly it isn't that option that causes a problem for everyone. Sounds like something specific to your processor revision. Take care, Mark


Subject Author
Re: [gentoo-amd64] Possible Math Problem - Request For Verification [Solved] Frank Peters <frank.peters@×××××××.net>