Error when differentiating Explicit template class

[a17brah]

I noticed a weird behaviour when used EnzymeAD with an explicit template class. If the method bump is defined in the cpp file, I get this error "declare dso_local noundef double @_ZNK8RiskViewIdE4bumpEdd(ptr noundef nonnull align 8 dereferenceable(304), double noundef, double noundef) local_unnamed_addr #7
Assertion failed: 0 && "attempting to differentiate function without definition" "

template<typename T>
class RiskView {
public:
    RiskView();

    RiskView(Array<T> &times, Array<T> &strikes, Array<T> &forwards, Matrix<T> &spreads);

    T bump(T x, T t) const;;

    void out();

private:
    bool isDefault_;
    Array<T> times_;
    Array<T> strikes_;
    Array<T> forwards_;
    Matrix<T> spreads_;
    std::vector<Array<T>> logMoneyness_;
    std::vector<Array<T>> spreadsVec_;
    std::vector<Interpolator<T, SmoothStepInterpolation, FlatExtrapolation>> interpolators_;
};

//EnzymeAD works when this is defined in the header
template<typename T>
T RiskView<T>::bump(T x, T t) const { //error if defined in cpp
    if (!isDefault_) {
        //find index in t then interpolate index-1, index=> give linear interpolation of that.
        int index = search_sorted<T>(t, times_.data(), times_.size(), true);
        //case index = 0 => t< times[0]
        if (index == 0) {
            T t_right = times_[0];
            T y_right = interpolators_[0].interpolate(x);
            return t * y_right / t_right;
        } else {
            T t_left = times_[index - 1];
            T t_right = times_[index];
            T y_left = interpolators_[index - 1].interpolate(x);;
            T y_right = interpolators_[index].interpolate(x);
            return y_left + (t - t_left) * (y_right - y_left) / (t_right - t_left);
        }
    }
    return 0.0;
}

[wsmoses]

Mind pasting the whole file (perhaps in an Enzyme explorer link enzyme.mit.edu/explorer)?

[a17brah]

https://fwd.gymni.ch/CmHXUs. When implementing the f in a CPP file, the Enzyme tool crashes with the following error message:

[2/3] Building CXX object CMakeFiles/testEnzyme.dir/main.cpp.o
FAILED: CMakeFiles/testEnzyme.dir/main.cpp.o
/home/linuxbrew/.linuxbrew/bin/clang++ -std=gnu++17 -O3 -DNDEBUG -fcolor-diagnostics -fplugin=/home/linuxbrew/.linuxbrew/Cellar/enzyme/0.0.89/lib/ClangEnzyme-16.so -MD -MT CMakeFiles/testEnzyme.dir/main.cpp.o -MF CMakeFiles/testEnzyme.dir/main.cpp.o.d -o CMakeFiles/testEnzyme.dir/main.cpp.o -c /mnt/c/Users/alijm/CLionProjects/testEnzyme/main.cpp
error: Enzyme: No reverse pass found for _ZNK7MyClassIdE1fEd
at context: %3 = tail call noundef double @_ZNK7MyClassIdE1fEd(ptr noundef nonnull align 8 dereferenceable(8) %1, double noundef %0) #9

[wsmoses]

Ah sorry I didn't fully read your post properly. If you have the function in a different cpp file and Enzyme deduces it needs to be diffeerentiated (it detects this here), you need to enable multisource support with LLDEnzyme or an alternate mechanism.

[a17brah]

So use LLDEnzyme flags instead of clang, or do I need to add anything else?

[ZuseZ4]

We updated our docs here to describe the differences: https://enzyme.mit.edu/getting_started/UsingEnzyme/#differentiating-cc
It also contains a link to a cmake template which hopefully works for you, please let us know if not!