Re: [eigen] any remaining issues blocking beta1, speak up!

[Gael Guennebaud <gael.guennebaud@xxxxxxxxx>]

here is a simplified version:

#include <iostream>
#include <Eigen/Dense>

template<typename A, typename B> EIGEN_DONT_INLINE int foo(const A& a,
const B& b)
{
  return (a - b).sum() <= 0;
}

int main()
{
  Eigen::Matrix<float,1,1> v;
  v.setOnes();
  return foo(v.colwise().maxCoeff(),v);
}

which, again, fails with gcc-4.3 + strict-aliasing only....
investigating to see if I can find a workaround.

gael

On Sat, Jul 3, 2010 at 1:03 PM, Jitse Niesen <jitse@xxxxxxxxxxxxxxxxx> wrote:
> On Sat, 3 Jul 2010, Benoit Jacob wrote:
>
>> All is in the title. Can we release beta1 this Saturday?
>
> There is also the stable_norm_1 test that is failing on gcc 4.3. This seems
> to be a mistake in Eigen itself.
>
> See the previous email I wrote:
>
> On Thu, 1 Jul 2010, Jitse Niesen wrote:
>>
>> Date: Thu, 1 Jul 2010 11:02:51 +0100 (BST)
>> From: Jitse Niesen <jitse@xxxxxxxxxxxxxxxxx>
>> To: Eigen mailinglist <eigen@xxxxxxxxxxxxxxxxxxx>
>> Subject: Failing stable_norm_1 test
>>
>> Hello,
>>
>> I just spent some time on the stable_norm_1 test, which fails on both my
>> computer and Gael's computer when using gcc 4.3. It looks similar to the
>> issue
>> which you solved by the empty struct magic (well done!).
>>
>> The details are as follows. I constructed the following (fairly) minimal
>> test
>> example:
>>
>> #include <iostream>
>> #include <Eigen/Dense>
>>
>> int main()
>> {
>>  Eigen::Matrix<float,1,1> v;
>>  v(0,0) = 0.1;
>>  std::cerr << "blue norm = " << v.colwise().blueNorm() << "\n";
>>  std::cerr << "status = " <<
>> v.colwise().hypotNorm().isApprox(v.colwise().norm(), 1e-4) << "\n";
>> }
>>
>> When compiling with g++ (version 4.3.3) -O2 -g and running under valgrind,
>> this
>> produces:
>>
>> Use of uninitialised value of size 4
>>    at 0x8048F28: bool
>> Eigen::DenseBase<Eigen::PartialReduxExpr<Eigen::Matrix<float, 1, 1, 0, 1,
>> 1>,
>> Eigen::ei_member_hypotNorm<float>, 0>
>> >::isApprox<Eigen::PartialReduxExpr<Eigen::Matrix<float, 1, 1, 0, 1, 1>,
>> Eigen::ei_member_norm<float>, 0>
>> >(Eigen::DenseBase<Eigen::PartialReduxExpr<Eigen::Matrix<float, 1, 1, 0,
>> > 1, 1>,
>> Eigen::ei_member_norm<float>, 0> > const&, float) const (in
>> /scratch/1/users/jitse/work/c/eigen/eigenfoo)
>>    by 0x8048AF5: main (in /scratch/1/users/jitse/work/c/eigen/eigenfoo)
>>
>> and the same error with the same stack trace a bit later, at 0x8048F2A.
>>
>> The result of the program is also wrong: it should print status = 1, but
>> it
>> says status = 0.
>>
>> The error goes away when compiling with -fno-strict-aliasing.
>> I tried compiling with -Wstrict-aliasing=2 but that does not produce any
>> warnings.
>>
>> Over to the gurus!
>>
>> Cheers,
>> Jitse
>>
>
>
>