Re: [eigen] XLC Port: Part II - External definition of a template member function of a template class causing the problems?

[Benoit Jacob <jacob.benoit.1@xxxxxxxxx>]

And then try the same code but with the has_floating_point deferred
until after they are used:


#include<iostream>

template<typename T> struct has_floating_point;

template<typename T, bool IsFloat = has_floating_point<T>::ret>
struct print_if_it_has_floating_point
{
 static void run()
 {
   std::cout << "Doesn't have floating point." << std::endl;
 }
};

template<typename T>
struct print_if_it_has_floating_point<T, true>
{
 static void run()
 {
   std::cout << "Has floating point." << std::endl;
 }
};

template<>
struct has_floating_point<int>
{
 enum { ret = 0 };
};

template<>
struct has_floating_point<float>
{
 enum { ret = 1 };
};

template<>
struct has_floating_point<double>
{
 enum { ret = 1 };
};

int main()
{
 print_if_it_has_floating_point<int>::run();
 print_if_it_has_floating_point<float>::run();
 print_if_it_has_floating_point<double>::run();
}




2010/1/30 Benoit Jacob <jacob.benoit.1@xxxxxxxxx>:
> 2010/1/30 Benoit Jacob <jacob.benoit.1@xxxxxxxxx>:
>> 2010/1/30 Aron Ahmadia <aja2111@xxxxxxxxxxxx>:
>>> Hi Benoit,
>>>
>>> I got that code workarounding by inlining the template function member
>>> definitions into the class definition.  I decided to skip forward and
>>> see if there were any other big issues that were causing the XLC
>>> compiler to crash, and ei_traits appears to be another one.  The XLC
>>> compiler is complaining when it tries to instansiate the ei_traits
>>> template class using a single template argument (MatrixType) with the
>>> error that the undefined class is not valid:
>>>
>>> "eigen/Eigen/src/Core/util/ForwardDeclarations.h", line 46.30:
>>> 1540-1109 (S) The use of undefined class
>>> "Eigen::ei_traits<Eigen::Matrix<float,3,3,0,3,3> >" is not valid.
>>>
>>> My suspicion is that ei_traits is not defined in a manner that XLC
>>> approves of, or that it is bugging out for another reason.  I will
>>> spend some time investigating this week and try to narrow down exactly
>>> how and where XLC is breaking.  One possibility is that it can't
>>> handle a template class instantiation to resolve another template
>>> argument.  Another possibility is that it can't find a definition of
>>> ei_traits that it likes.  I think I can eliminate the second
>>> possibility by trying to explicitly instantiate an ei_traits object
>>> with the given argument.s
>>>
>>> Nevermind, I just tried it.  XLC is okay with this:
>>> Eigen::ei_traits<Eigen::Matrix<float,3,3,0,3,3> > a;
>>>
>>> and compiles, links, and runs it through a main.cpp routine.
>>> It gives the same errors about ei_traits with these lines of code:
>>> Eigen::Matrix<float,3,3,0,3,3> m;
>>> Matrix3f m3;
>>>
>>> "eigen/Eigen/src/Core/util/ForwardDeclarations.h", line 44.30:
>>> 1540-1109 (S) The use of undefined class
>>> "Eigen::ei_traits<Eigen::Matrix<float,3,3,0,3,3> >" is not valid.
>>>
>>> I think this points to your use of ei_traits here:
>>> template<typename MatrixType, int BlockRows=Dynamic, int BlockCols=Dynamic,
>>>  int _DirectAccessStatus =
>>> (ei_traits<MatrixType>::Flags&DirectAccessBit) ? HasDirectAccess :
>>> NoDirectAccess> class Block;
>>>
>>> Some other compiler errors in the code seem to indicate that XLC is
>>> unable to handle the instantiation of a template class to resolve a
>>> non-class template argument.
>>
>> Ah, thanks, I'm starting to understand and this makes sense. I really
>> hope that it is not the case:
>>
>>> that XLC is
>>> unable to handle the instantiation of a template class to resolve a
>>> non-class template argument.
>>
>> Because if that is the case, then it is virtually impossible to do any
>> template metaprogramming with XLC :( At least I can say that we are
>> doing this at many places and this is a very important device for us,
>> so if that is what XLC doesn't like, fixing it would involve a very
>> big set of changes and the resulting Eigen would be far clumsier
>> (right now I'm not even sure that's possible).
>
> OK, can you try this testcase to see if XLC really has a problem with
> the Eigen code that you pasted. This Eigen code is accessing an
> instantiation of a template class to give the default value of a
> template parameter. So here is a test case for that:
>
> #include<iostream>
>
> template<typename T> struct has_floating_point
> {
>  enum { ret = 0 };
> };
>
> template<>
> struct has_floating_point<float>
> {
>  enum { ret = 1 };
> };
>
> template<>
> struct has_floating_point<double>
> {
>  enum { ret = 1 };
> };
>
> template<typename T, bool IsFloat = has_floating_point<T>::ret>
> struct print_if_it_has_floating_point
> {
>  static void run()
>  {
>    std::cout << "Doesn't have floating point." << std::endl;
>  }
> };
>
> template<typename T>
> struct print_if_it_has_floating_point<T, true>
> {
>  static void run()
>  {
>    std::cout << "Has floating point." << std::endl;
>  }
> };
>
> int main()
> {
>  print_if_it_has_floating_point<int>::run();
>  print_if_it_has_floating_point<float>::run();
>  print_if_it_has_floating_point<double>::run();
> }
>
>
> Benoit
>
>
>
>>
>> Benoit
>>
>>
>>>
>>> Cheers,
>>> Aron
>>>
>>> On Sat, Jan 30, 2010 at 4:56 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
>>>> 2010/1/27 Aron Ahmadia <aja2111@xxxxxxxxxxxx>:
>>>>> Hi all,
>>>>>
>>>>> I'm still looking at the port, and I've managed to narrow down the
>>>>> problem.  For those of you who've been following along at home, XLC
>>>>> has been throwing this error when trying to compile the Eigen files:
>>>>>                                              [0]
>>>>> "eigen/Eigen/src/Core/SelfAdjointView.h", line 147.81: 1540-0716 (S)
>>>>> The template argument "Eigen::SelfAdjointView" does not match the
>>>>> template parameter "class T".
>>>>> "eigen/Eigen/src/Core/SelfAdjointView.h", line 134.112: 1540-0716 (S)
>>>>> The template argument "Eigen::SelfAdjointView" does not match the
>>>>> template parameter "class T".
>>>>>
>>>>> Suspiciously, there's no trace of SelfAdjointView being used as a
>>>>> template parameter argument anywhere in there, or any trace of a
>>>>> parameter named 'class T'.
>>>>>
>>>>> So I decided to create a new test file, slowly adding in the Eigen
>>>>> header files from Core until I got compiler errors.  Here's the
>>>>> current file: http://pastebin.com/m267235e7
>>>>>
>>>>> If you'll notice, SelfAdjointView.h is being successfully included
>>>>> here.  What causes the breakage is SelfadjointProduct.h.  This
>>>>> actually isn't that surprising, since a function that declared in
>>>>> SelfAdjointView.h is later defined in SelfadjointProduct.h (By the
>>>>> way, should this be renamed to SelfAdjointProduct.h to fit the rest of
>>>>> the naming scheme better?)
>>>>>
>>>>> Here is the declaration and the definition:
>>>>>
>>>>> template<typename DerivedU>
>>>>> SelfAdjointView& rankUpdate(const MatrixBase<DerivedU>& u, Scalar alpha)
>>>>>
>>>>>
>>>>> template<typename MatrixType, unsigned int UpLo>
>>>>> template<typename DerivedU>
>>>>> SelfAdjointView<MatrixType,UpLo>& SelfAdjointView<MatrixType,UpLo>
>>>>> ::rankUpdate(const MatrixBase<DerivedU>& u, Scalar alpha)
>>>>> {
>>>>>  typedef ei_blas_traits<DerivedU> UBlasTraits;
>>>>>  typedef typename UBlasTraits::DirectLinearAccessType ActualUType;
>>>>>  typedef typename ei_cleantype<ActualUType>::type _ActualUType;
>>>>>  const ActualUType actualU = UBlasTraits::extract(u.derived());
>>>>>
>>>>>  Scalar actualAlpha = alpha * UBlasTraits::extractScalarFactor(u.derived());
>>>>>
>>>>>  enum { IsRowMajor = (ei_traits<MatrixType>::Flags&RowMajorBit) ? 1 : 0 };
>>>>>
>>>>>  ei_selfadjoint_product<Scalar,
>>>>>    _ActualUType::Flags&RowMajorBit ? RowMajor : ColMajor,
>>>>>    ei_traits<MatrixType>::Flags&RowMajorBit ? RowMajor : ColMajor,
>>>>>    !UBlasTraits::NeedToConjugate, UpLo>
>>>>>    ::run(_expression().cols(), actualU.cols(), &actualU.coeff(0,0),
>>>>> actualU.stride(),
>>>>>          const_cast<Scalar*>(_expression().data()),
>>>>> _expression().stride(), actualAlpha);
>>>>>
>>>>>  return *this;
>>>>> }
>>>>>
>>>>> So according to this page here:
>>>>> http://www.comeaucomputing.com/techtalk/templates
>>>>>
>>>>> You're not allowed to do the above because SelfAdjointView is the
>>>>> 'primary template argument'.  Unfortunately, the code refuses to
>>>>> compile if the template arguments are removed.
>>>>
>>>> I'm sorry, I still don't understand what is not allowed with the code
>>>> that you pasted here?
>>>>
>>>> Benoit
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>