PreconditionerCPUMatrixToGPUMatrix.hpp

/*
  Copyright 2025 Equinor ASA

  This file is part of the Open Porous Media project (OPM).

  OPM is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  OPM is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef OPM_PRECONDITIONERCPUMATRIXTOGPUMATRIX_HPP
#define OPM_PRECONDITIONERCPUMATRIXTOGPUMATRIX_HPP
#include "opm/simulators/linalg/gpuistl/GpuSparseMatrixWrapper.hpp"
#include <dune/istl/preconditioner.hh>
#include <opm/simulators/linalg/PreconditionerWithUpdate.hpp>
#include <opm/simulators/linalg/gpuistl/GpuVector.hpp>
#include <opm/simulators/linalg/gpuistl/PreconditionerHolder.hpp>
#include <opm/simulators/linalg/gpuistl/detail/preconditioner_should_call_post_pre.hpp>


namespace Opm::gpuistl
{
template <class X, class Y, class CudaPreconditionerType, class CPUMatrixType>
class PreconditionerCPUMatrixToGPUMatrix : public Dune::PreconditionerWithUpdate<X, Y>
{
public:
    using domain_type = X;
    using range_type = Y;
    using field_type = typename X::field_type;


    template <typename... Args>
    explicit PreconditionerCPUMatrixToGPUMatrix(const CPUMatrixType& A, Args&&... args)
        : m_cpuMatrix(A)
        , m_gpuMatrix(GpuSparseMatrixWrapper<field_type>::fromMatrix(A))
        , m_underlyingPreconditioner(m_gpuMatrix, std::forward<Args>(args)...)
    {
    }


    void pre([[maybe_unused]] X& x, [[maybe_unused]] Y& b) override
    {
        static_assert(!detail::shouldCallPreconditionerPre<CudaPreconditionerType>(),
                      "We currently do not support Preconditioner::pre().");
    }


    void apply(X& v, const Y& d) override
    {
        m_underlyingPreconditioner.apply(v, d);
    }


    void post([[maybe_unused]] X& x) override
    {
        static_assert(!detail::shouldCallPreconditionerPost<CudaPreconditionerType>(),
                      "We currently do not support Preconditioner::post().");
    }


    Dune::SolverCategory::Category category() const override
    {
        return m_underlyingPreconditioner.category();
    }

    void update() override
    {
        m_gpuMatrix.updateNonzeroValues(m_cpuMatrix, true);
        m_underlyingPreconditioner.update();
    }

    static constexpr bool shouldCallPre()
    {
        return detail::shouldCallPreconditionerPost<CudaPreconditionerType>();
    }
    static constexpr bool shouldCallPost()
    {
        return detail::shouldCallPreconditionerPre<CudaPreconditionerType>();
    }

    virtual bool hasPerfectUpdate() const override
    {
        return m_underlyingPreconditioner.hasPerfectUpdate();
    }

private:
    const CPUMatrixType& m_cpuMatrix;
    GpuSparseMatrixWrapper<field_type> m_gpuMatrix;

    CudaPreconditionerType m_underlyingPreconditioner;
};
} // end namespace Opm::gpuistl

#endif // OPM_PRECONDITIONERCPUMATRIXTOGPUMATRIX_HPP