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. > > The new behavior is that under certain conditions a certain matrix inner > product produces undefined floats, that should not be there. If the code > is executed inside any function it fails but if the same code is reexecuted > at the ghci prompt it works. Here is the gist of the code that I'm running > > main = do > ... lots of computations and let clauses > -- get a submatrix > viewMatbotk wstart nsua su 1 suw > -- get another submatrix > viewMatbotk 0 nsua arrstart npaths sua > -- complex non conjugated inner product (multiply the two submatrices) > mulCFtF > mprint > > If this is executed either in ghci as main or from a Dos prompt I get > a matrix filled with bad values including a few that look like > -1.#IND+1.87514i > > If I recompile everything in ghc-6.6.1 it works like charm. I make sure > that I have deleted all the .o and .hi files. There is a dll that contains > a C library I link to via running dlltool.exe. If I print out all the > function inputs to the function viewMatbotk and then call them > interactively in ghc 6.8.1 and call mulCFtF interactively it works > correctly. both viewMatbotk and mulCFtF are C routines pulled in from the > external library. > > I am at a complete loss how to debug this or how to pin down what exactly > has changed between 6.6.1 and 6.8.1 that breaks this code so badly. This > type of error stinks of some kind of memory issue, e.g. corrupted pointers. > Any suggestions would be appreciated. Unfortunately the code base is > rather involved and potentially proprietary so I can't publish all of the > details. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
