[Haskell-cafe] ghc 6.8.1 bug?

Alberto Ruiz aruiz at um.es
Thu Nov 15 15:18:39 EST 2007

On Thursday 15 November 2007 19:58, SevenThunders wrote:
> Alberto Ruiz-2 wrote:
> > Hello,
> >
> > I have had exactly the same problem with my bindings to GSL, BLAS and
> > 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
> Arrgh, the fix of using -fvia-C doesn't seem to be working for me.
> You got my hopes up for a moment :).
> I also am calling BLAS via C bindings.
> I am going to try to distill my case down to the bare minimum if possible
> and then provide an example. It may take a while.

Hmm, I' sorry... all seems to work well for me if I set -O -fvia-C for 
building the library and for final program compilation. But I will also try 
to find a minimum test case. In the meantime I have sent to Ian information 
to expose the problem with my library, although I know that such large amount 
of code will not be very helpful.

Have you tested ghc-6.6.1 with -O -fasm?

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