// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
#ifndef DUNE_COMMON_SIMD_HH
#define DUNE_COMMON_SIMD_HH

#warning dune/common/simd.hh is deprecated.
#warning Use the new infrastructure from dune/common/simd/simd.h instead.

/**
   \file

   \brief Abstractions for support of dedicated SIMD data types

   Libraries like Vc (https://github.com/VcDevel/Vc) add high-level
   data types for SIMD (or vectorization) support in C++.  Most of
   these operations mimic the behavior of a numerical data type. Some
   boolean operations can not be implemented in a compatible way to
   trivial data types.

   This header contains additional abstractions to help writing code
   that works with trivial numerical data types (like double) and Vc
   vectorization data types.

   See also the conditional.hh and range_utils.hh headers.

   \deprecated Use the newer simd architecture from dune/common/simd/simd.hh
               instead.
 */

#include <cassert>
#include <cstddef>
#include <type_traits>
#include <utility>

#include <dune/common/conditional.hh>
#include <dune/common/debugalign.hh>
#include <dune/common/rangeutilities.hh>
#if HAVE_VC
// include Vc part of new simd interface to provide compatibility for
// functionality that has been switched over.
#include <dune/common/simd/vc.hh>
#endif
#include <dune/common/typetraits.hh>
#include <dune/common/vc.hh>

namespace Dune
{

#if HAVE_VC
  namespace VcImpl {
    //! A reference-like proxy for elements of random-access vectors.
    /**
     * This is necessary because Vc's lane-access operation return a proxy
     * that cannot constructed by non-Vc code (i.e. code that isn't
     * explicitly declared `friend`).  This means in particular that there
     * is no copy/move constructor, meaning we cannot return such proxies
     * from our own functions, such as `lane()`.  To work around this, we
     * define our own proxy class which internally holds a reference to the
     * vector and a lane index.
     */
    template<class V>
    class Proxy
    {
      static_assert(std::is_same<V, std::decay_t<V> >::value, "Class Proxy "
                    "may only be instantiated with unqualified types");
    public:
      using value_type = typename V::value_type;

    private:
      static_assert(std::is_arithmetic<value_type>::value,
                    "Only arithmetic types are supported");
      V &vec_;
      std::size_t idx_;

    public:
      Proxy(std::size_t idx, V &vec)
        : vec_(vec), idx_(idx)
      { }

      operator value_type() const { return vec_[idx_]; }

      // postfix operators

      template<class T = value_type,
               class = std::enable_if_t<!std::is_same<T, bool>::value> >
      value_type operator++(int) { return vec_[idx_]++; }
      template<class T = value_type,
               class = std::enable_if_t<!std::is_same<T, bool>::value> >
      value_type operator--(int) { return vec_[idx_]--; }

      // unary (prefix) operators
      template<class T = value_type,
               class = std::enable_if_t<!std::is_same<T, bool>::value> >
      Proxy &operator++() { ++(vec_[idx_]); return *this; }
      template<class T = value_type,
               class = std::enable_if_t<!std::is_same<T, bool>::value> >
      Proxy &operator--() { --(vec_[idx_]); return *this; }
      decltype(auto) operator!() const { return !(vec_[idx_]); }
      decltype(auto) operator+() const { return +(vec_[idx_]); }
      decltype(auto) operator-() const { return -(vec_[idx_]); }
      template<class T = value_type,
               class = std::enable_if_t<std::is_integral<T>::value> >
      decltype(auto) operator~() const { return ~(vec_[idx_]); }

      // binary operators
#define DUNE_SIMD_VC_BINARY_OP(OP)                                      \
      template<class T>                                                 \
      auto operator OP(T &&o) const                                     \
        -> decltype(vec_[idx_] OP valueCast(std::forward<T>(o)))        \
      {                                                                 \
        return vec_[idx_] OP valueCast(std::forward<T>(o));             \
      }                                                                 \
      static_assert(true, "Require semicolon to unconfuse editors")

      DUNE_SIMD_VC_BINARY_OP(*);
      DUNE_SIMD_VC_BINARY_OP(/);
      DUNE_SIMD_VC_BINARY_OP(%);

      DUNE_SIMD_VC_BINARY_OP(+);
      DUNE_SIMD_VC_BINARY_OP(-);

      DUNE_SIMD_VC_BINARY_OP(<<);
      DUNE_SIMD_VC_BINARY_OP(>>);

      DUNE_SIMD_VC_BINARY_OP(<);
      DUNE_SIMD_VC_BINARY_OP(>);
      DUNE_SIMD_VC_BINARY_OP(<=);
      DUNE_SIMD_VC_BINARY_OP(>=);

      DUNE_SIMD_VC_BINARY_OP(==);
      DUNE_SIMD_VC_BINARY_OP(!=);

      DUNE_SIMD_VC_BINARY_OP(&);
      DUNE_SIMD_VC_BINARY_OP(^);
      DUNE_SIMD_VC_BINARY_OP(|);

      DUNE_SIMD_VC_BINARY_OP(&&);
      DUNE_SIMD_VC_BINARY_OP(||);
#undef DUNE_SIMD_VC_BINARY_OP

#define DUNE_SIMD_VC_ASSIGNMENT(OP)                                   \
      template<class T>                                               \
      auto operator OP(T &&o)                                         \
        -> std::enable_if_t<AlwaysTrue<decltype(                      \
                 vec_[idx_] OP valueCast(std::forward<T>(o))          \
               )>::value, Proxy&>                                     \
      {                                                               \
        vec_[idx_] OP valueCast(std::forward<T>(o));                  \
        return *this;                                                 \
      }                                                               \
      static_assert(true, "Require semicolon to unconfuse editors")

      DUNE_SIMD_VC_ASSIGNMENT(=);
      DUNE_SIMD_VC_ASSIGNMENT(*=);
      DUNE_SIMD_VC_ASSIGNMENT(/=);
      DUNE_SIMD_VC_ASSIGNMENT(%=);
      DUNE_SIMD_VC_ASSIGNMENT(+=);
      DUNE_SIMD_VC_ASSIGNMENT(-=);
      DUNE_SIMD_VC_ASSIGNMENT(<<=);
      DUNE_SIMD_VC_ASSIGNMENT(>>=);
      DUNE_SIMD_VC_ASSIGNMENT(&=);
      DUNE_SIMD_VC_ASSIGNMENT(^=);
      DUNE_SIMD_VC_ASSIGNMENT(|=);
#undef DUNE_SIMD_VC_ASSIGNMENT

      // swap on proxies swaps the proxied vector entries.  As such, it
      // applies to rvalues of proxies too, not just lvalues
      template<class V1, class V2>
      friend void swap(Proxy<V1>, Proxy<V2>);

      template<class T>
      friend void swap(Proxy p1, T& s2)
      {
        // don't use swap() ourselves -- not supported by Vc 1.3.0 (but is
        // supported by Vc 1.3.2)
        T tmp = p1.vec_[p1.idx_];
        p1.vec_[p1.idx_] = s2;
        s2 = tmp;
      }

      template<class T>
      friend void swap(T& s1, Proxy p2)
      {
        T tmp = s1;
        s1 = p2.vec_[p2.idx_];
        p2.vec_[p2.idx_] = tmp;
      }
    };

    template<class V1, class V2>
    void swap(Proxy<V1> p1, Proxy<V2> p2)
    {
      typename V1::value_type tmp = p1.vec_[p1.idx_];
      p1.vec_[p1.idx_] = p2.vec_[p2.idx_];
      p2.vec_[p2.idx_] = tmp;
    }
  } //  namespace VcImpl
#endif // HAVE_VC

  template<typename T>
  struct SimdScalarTypeTraits
  {
    using type = T;
  };

  template<typename T>
  using SimdScalar = typename SimdScalarTypeTraits<T>::type;

#if HAVE_VC
  /*
    Add Vc specializations for the SimdScalarTypeTraits trais class
   */
  template<typename T, typename A>
  struct SimdScalarTypeTraits< Vc::Vector<T,A> >
  {
    using type = T;
  };

  template<typename T, std::size_t N, typename V, std::size_t M>
  struct SimdScalarTypeTraits< Vc::SimdArray<T,N,V,M> >
  {
    using type = T;
  };
#endif // HAVE_VC

  //! deduce the underlying scalar data type of an AlignedNumber
  template<typename T, std::size_t align>
  struct SimdScalarTypeTraits< AlignedNumber<T,align> >
  {
    using type = T;
  };

  template<typename V, typename = void>
  struct SimdIndexTypeTraits {
    using type = std::size_t;
  };

  //! An simd vector of indices corresponding to a simd vector V
  /**
   * lanes(T()) == lanes(SimdIndex<T>()) holds.
   *
   * \note The size of the elements of a SimdIndex isn't very well-defined.
   *       Be careful.
   */
  template<typename V>
  using SimdIndex = typename SimdIndexTypeTraits<V>::type;

#if HAVE_VC
  template<typename T, typename A>
  struct SimdIndexTypeTraits<Vc::Vector<T, A> > {
    using type = typename Vc::Vector<T, A>::index_type;
  };

  template<typename T, std::size_t n, typename V>
  struct SimdIndexTypeTraits<Vc::SimdArray<T, n, V> > {
    using type = typename Vc::SimdArray<T, n, V>::index_type;
  };
#endif // HAVE_VC

  template<typename V, typename = void>
  struct SimdMaskTypeTraits {
    using type = bool;
  };

  //! A simd vector of truth values corresponding to a simd vector V
  /**
   * lanes(T()) == lanes(SimdMask<T>()) holds.
   */
  template<typename V>
  using SimdMask = typename SimdMaskTypeTraits<V>::type;

#if HAVE_VC
  template<typename T, typename A>
  struct SimdMaskTypeTraits<Vc::Vector<T, A> > {
    using type = typename Vc::Vector<T, A>::mask_type;
  };

  template<typename T, std::size_t n, typename V>
  struct SimdMaskTypeTraits<Vc::SimdArray<T, n, V> > {
    using type = typename Vc::SimdArray<T, n, V>::mask_type;
  };
#endif // HAVE_VC

#if HAVE_VC
  /*
    Add Vc specializations for cond(), see conditional.hh
   */
  template<typename T, typename A>
  Vc::Vector<T,A> cond(const Vc::Mask<T,A> & b,
    const Vc::Vector<T,A> & v1,
    const Vc::Vector<T,A> & v2)
  {
    return std::move(Vc::iif(b, v1, v2));
  }

  template<typename T, std::size_t N, typename V, std::size_t M>
  Vc::SimdArray<T,N,V,M> cond(const typename Vc::SimdArray<T,N,V,M>::mask_type & b,
    const Vc::SimdArray<T,N,V,M> & v1,
    const Vc::SimdArray<T,N,V,M> & v2)
  {
    return std::move(Vc::iif(b, v1, v2));
  }
#endif // HAVE_VC

#if HAVE_VC
  /*
    Add Vc specializations for several boolean operations, see rangeutitlities.hh:

    max_value, min_value, any_true, all_true
   */
  template<typename T, typename A>
  T max_value(const Vc::Vector<T,A> & v)
  {
    return v.max();
  }

  template<typename T, std::size_t N, typename V, std::size_t M>
  double max_value(const Vc::SimdArray<T,N,V,M> & v)
  {
    return v.max();
  }

  template<typename T, typename A>
  T min_value(const Vc::Vector<T,A> & v)
  {
    return v.min();
  }

  template<typename T, std::size_t N, typename V, std::size_t M>
  double min_value(const Vc::SimdArray<T,N,V,M> & v)
  {
    return v.min();
  }

  template<typename T, typename A>
  bool any_true(const Vc::Mask<T,A> & v)
  {
    return Vc::any_of(v);
  }

  template<typename T, std::size_t N, typename V, std::size_t M>
  bool any_true(const Vc::SimdMaskArray<T,N,V,M> & v)
  {
    return Vc::any_of(v);
  }

  template<typename T, typename A>
  bool all_true(const Vc::Mask<T,A> & v)
  {
    return Vc::all_of(v);
  }

  template<typename T, std::size_t N, typename V, std::size_t M>
  bool all_true(const Vc::SimdMaskArray<T,N,V,M> & v)
  {
    return Vc::all_of(v);
  }
#endif // HAVE_VC

  //! get the number of lanes of a simd vector (scalar version)
  template<class T>
  std::size_t lanes(const T &) { return 1; }

  //! access a lane of a simd vector (scalar version)
  template<class T>
  T lane(std::size_t l, const T &v)
  {
    assert(l == 0);
    return v;
  }

  //! access a lane of a simd vector (scalar version)
  template<class T>
  T &lane(std::size_t l, T &v)
  {
    assert(l == 0);
    return v;
  }

#if HAVE_VC
  template<class T, class A>
  std::size_t lanes(const Vc::Vector<T, A> &)
  {
    return Vc::Vector<T, A>::size();
  }

  template<class T, class A>
  T lane(std::size_t l, const Vc::Vector<T, A> &v)
  {
    assert(l < lanes(v));
    return v[l];
  }

  template<class T, class A>
  auto lane(std::size_t l, Vc::Vector<T, A> &v)
  {
    assert(l < lanes(v));
    return VcImpl::Proxy<Vc::Vector<T, A> >{l, v};
  }

  template<class T, std::size_t n, class V>
  std::size_t lanes(const Vc::SimdArray<T, n, V> &)
  {
    return n;
  }

  template<class T, std::size_t n, class V>
  T lane(std::size_t l, const Vc::SimdArray<T, n, V> &v)
  {
    assert(l < n);
    return v[l];
  }

  template<class T, std::size_t n, class V>
  auto lane(std::size_t l, Vc::SimdArray<T, n, V> &v)
  {
    assert(l < n);
    return VcImpl::Proxy<Vc::SimdArray<T, n, V> >{l, v};
  }

  template<class T, std::size_t n, class V>
  std::size_t lanes(const Vc::SimdMaskArray<T, n, V> &)
  {
    return n;
  }

  template<class T, std::size_t n, class V>
  bool lane(std::size_t l, const Vc::SimdMaskArray<T, n, V> &v)
  {
    assert(l < n);
    return v[l];
  }

  template<class T, std::size_t n, class V>
  auto lane(std::size_t l, Vc::SimdMaskArray<T, n, V> &v)
  {
    assert(l < n);
    return VcImpl::Proxy<Vc::SimdMaskArray<T, n, V> >{l, v};
  }
#endif // HAVE_VC

  //! masked Simd assignment (scalar version)
  /**
   * Assign \c src to \c dest for those lanes where \c mask is true.
   */
  template<class T>
  void assign(T &dst, const T &src, bool mask)
  {
    if(mask) dst = src;
  }

#if HAVE_VC
  /*
    Add Vc specializations for masked assignment
  */
  template<class T, class A>
  void assign(Vc::Vector<T, A> &dst, const Vc::Vector<T, A> &src,
              typename Vc::Vector<T, A>::mask_type mask)
  {
    dst(mask) = src;
  }

  template<class T, std::size_t n, class V>
  void assign(Vc::SimdArray<T, n, V> &dst, const Vc::SimdArray<T, n, V> &src,
              typename Vc::SimdArray<T, n, V>::mask_type mask)
  {
    dst(mask) = src;
  }
#endif // HAVE_VC

  template<class T>
  void swap(T &v1, T &v2, bool mask)
  {
    using std::swap;
    if(mask) swap(v1, v2);
  }

#if HAVE_VC
  /*
    Add Vc specializations for masked swap
  */
  template<class T, class A>
  void swap(Vc::Vector<T, A> &v1, Vc::Vector<T, A> &v2,
            typename Vc::Vector<T, A>::mask_type mask)
  {
    auto tmp = v1;
    v1(mask) = v2;
    v2(mask) = tmp;
  }

  template<class T, std::size_t n, class V>
  void swap(Vc::SimdArray<T, n, V> &v1, Vc::SimdArray<T, n, V> &v2,
            typename Vc::SimdArray<T, n, V>::mask_type mask)
  {
    auto tmp = v1;
    v1(mask) = v2;
    v2(mask) = tmp;
  }
#endif // HAVE_VC

} // end namespace Dune

#endif // DUNE_COMMON_SIMD_HH