[Haskell-cafe] ghc 6.8.1 bug?

[Alberto Ruiz]

Simon, I have only tested 32-bit machines, I will try to test also on 64-bit.

Michael, I have also observed strange ATLAS behavior. For example, I can make 
atlas3-sse2 segfault on big matrices (1000x1000) in ubuntu 6.06 and 7.04, so 
I typically use atlas3-base. In fact, I found a similar problem:

http://article.gmane.org/gmane.linux.debian.devel.bugs.general/323065

(However, atlas3-sse2 seems to work well in ubuntu 7.10...)

But I have removed ATLAS and the problem persists even with the basic refblas3 
and lapack available in my ubuntu 6.06: lapack3-dev 3.0.2000531a-6ubuntu2. 
And I can even produce errors on GSL functions.

In my particular case all errors disappear if I set -O0 or -O -fvia-C. I will 
try to find a minimal test case exposing the problem with -fasm.

Alberto


On Friday 16 November 2007 11:30, Michael McNeil Forbes wrote:
> Just out of curiosity, what LAPACK and BLAS implementation is causing
> problems?  I have no idea if there is anything related, but I have
> been having similar sounding problems with python when using the
> latest ATLAS library on 64 bit core 2 machines.  I am beginning to
> suspect that there may be something wrong in ATLAS, but I don't have
> any definite evidence yet because the bug is also rather elusive here.
>
> Michael.
>
> On 16 Nov 2007, at 2:13 AM, Simon Peyton-Jones wrote:
> > Alberto, SevenThunders, Joel,
> >
> > Glark. This is not good. Thank you for being so polite about it.
> > And thanks for working on a reproducible test case -- without that
> > we are 100% stuck.
> >
> > We did fix one just-possibly-related bug in 6.8 recently, which
> > concerned the use of {-# UNPACK #-} on strict Double-sized fields
> > in fixed, top-level data structures. I think it was only wrong on a
> > 64-bit machine.
> > http://www.haskell.org/pipermail/glasgow-haskell-users/2007-
> > November/013454.html
> > What is the word size on your machine?
> >
> > But that may well be a complete red herring.  We'll stand by.
> >
> > Simon
> >
> > | -----Original Message-----
> > | From: haskell-cafe-bounces at haskell.org [mailto:haskell-cafe-
> >
> > bounces at haskell.org] On Behalf Of Alberto Ruiz
> >
> > | Sent: 15 November 2007 08:44
> > | To: haskell-cafe at haskell.org
> > | Subject: Re: [Haskell-cafe] ghc 6.8.1 bug?
> > |
> > | Hello,
> > |
> > | I have had exactly the same problem with my bindings to GSL, BLAS
> >
> > and LAPACK.
> >
> > | The foreign functions (!) randomly (but very frequently) produced
> >
> > NaN with
> >
> > | ghc-6.8.1 -O. As usual, I first thought that I had a subtle bug
> >
> > related to
> >
> > | the foreign pointers, but after a lot of refactoring,
> >
> > experiments, and
> >
> > | tracing everything, I'm reasonably sure that memory is safely
> >
> > used. What I
> >
> > | have found is that the same errors can be reproduced on ghc-6.6.1
> > | with -O -fasm. So I tried -O -fvia-C on ghc-6.8.1 (which now it
> >
> > is not the
> >
> > | default) and apparently everything works well. So it seems that
> >
> > now the ffi
> >
> > | requires and additional and explicit -fvia-C. In any case I don't
> >
> > know
> >
> > | why -fasm produces those strange NaN in precompiled foreign
> >
> > functions...
> >
> > | Alberto
> > |
> > | On Thursday 15 November 2007 09:05, SevenThunders wrote:
> > | > The good news is that my code compiles without error and much
> >
> > faster under
> >
> > | > ghc 6.8.1.
> > | > The bad news is that there appear to be subtle bugs that did
> >
> > not occur when
> >
> > | > I compiled things under
> > | > 6.6.1.  One issue is that my code is somewhat complex and links
> >
> > into a  C
> >
> > | > library as well.
> >
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>
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>
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