simdarrayhelper.h

/*  This file is part of the Vc library. {{{
Copyright © 2013-2015 Matthias Kretz <kretz@kde.org>

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the names of contributing organizations nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

}}}*/

#ifndef VC_COMMON_SIMDARRAYHELPER_H_
#define VC_COMMON_SIMDARRAYHELPER_H_

#include "macros.h"

namespace Vc_VERSIONED_NAMESPACE
{
// private_init {{{
namespace
{
static constexpr struct private_init_t {} private_init = {};
}  // unnamed namespace
// }}}

namespace Common
{


namespace Operations/*{{{*/
{
struct tag {};
#define Vc_DEFINE_OPERATION(name_)                                                       \
    struct name_ : public tag {                                                          \
        template <typename V, typename... Args>                                          \
        Vc_INTRINSIC void operator()(V &v, Args &&... args)                              \
        {                                                                                \
            v.name_(std::forward<Args>(args)...);                                        \
        }                                                                                \
    }
Vc_DEFINE_OPERATION(gather);
Vc_DEFINE_OPERATION(scatter);
Vc_DEFINE_OPERATION(load);
Vc_DEFINE_OPERATION(store);
Vc_DEFINE_OPERATION(setZero);
Vc_DEFINE_OPERATION(setZeroInverted);
Vc_DEFINE_OPERATION(assign);
#undef Vc_DEFINE_OPERATION
#define Vc_DEFINE_OPERATION(name_, code_)                                                \
    struct name_ : public tag {                                                          \
        template <typename V> Vc_INTRINSIC void operator()(V &v) { code_; }              \
    }
Vc_DEFINE_OPERATION(increment, ++(v));
Vc_DEFINE_OPERATION(decrement, --(v));
Vc_DEFINE_OPERATION(random, v = V::Random());
#undef Vc_DEFINE_OPERATION
#define Vc_DEFINE_OPERATION_FORWARD(name_)                                               \
    struct Forward_##name_ : public tag                                                  \
    {                                                                                    \
        template <typename... Args, typename = decltype(name_(std::declval<Args>()...))> \
        Vc_INTRINSIC void operator()(decltype(name_(std::declval<Args>()...)) &v,        \
                                     Args &&... args)                                    \
        {                                                                                \
            v = name_(std::forward<Args>(args)...);                                      \
        }                                                                                \
        template <typename... Args, typename = decltype(name_(std::declval<Args>()...))> \
        Vc_INTRINSIC void operator()(std::nullptr_t, Args && ... args)                   \
        {                                                                                \
            name_(std::forward<Args>(args)...);                                          \
        }                                                                                \
    }
Vc_DEFINE_OPERATION_FORWARD(abs);
Vc_DEFINE_OPERATION_FORWARD(asin);
Vc_DEFINE_OPERATION_FORWARD(atan);
Vc_DEFINE_OPERATION_FORWARD(atan2);
Vc_DEFINE_OPERATION_FORWARD(cos);
Vc_DEFINE_OPERATION_FORWARD(ceil);
Vc_DEFINE_OPERATION_FORWARD(copysign);
Vc_DEFINE_OPERATION_FORWARD(exp);
Vc_DEFINE_OPERATION_FORWARD(exponent);
Vc_DEFINE_OPERATION_FORWARD(fma);
Vc_DEFINE_OPERATION_FORWARD(floor);
Vc_DEFINE_OPERATION_FORWARD(frexp);
Vc_DEFINE_OPERATION_FORWARD(isfinite);
Vc_DEFINE_OPERATION_FORWARD(isinf);
Vc_DEFINE_OPERATION_FORWARD(isnan);
Vc_DEFINE_OPERATION_FORWARD(isnegative);
Vc_DEFINE_OPERATION_FORWARD(ldexp);
Vc_DEFINE_OPERATION_FORWARD(log);
Vc_DEFINE_OPERATION_FORWARD(log10);
Vc_DEFINE_OPERATION_FORWARD(log2);
Vc_DEFINE_OPERATION_FORWARD(reciprocal);
Vc_DEFINE_OPERATION_FORWARD(round);
Vc_DEFINE_OPERATION_FORWARD(rsqrt);
Vc_DEFINE_OPERATION_FORWARD(sin);
Vc_DEFINE_OPERATION_FORWARD(sincos);
Vc_DEFINE_OPERATION_FORWARD(sqrt);
Vc_DEFINE_OPERATION_FORWARD(trunc);
Vc_DEFINE_OPERATION_FORWARD(min);
Vc_DEFINE_OPERATION_FORWARD(max);
#undef Vc_DEFINE_OPERATION_FORWARD
template<typename T> using is_operation = std::is_base_of<tag, T>;
}  // namespace Operations }}}

template <typename T_, std::size_t Pieces_, std::size_t Index_> struct Segment/*{{{*/
{
    static_assert(Index_ < Pieces_, "You found a bug in Vc. Please report.");

    using type = T_;
    using type_decayed = typename std::decay<type>::type;
    static constexpr std::size_t Pieces = Pieces_;
    static constexpr std::size_t Index = Index_;
    using simd_array_type = SimdArray<
        typename std::conditional<Traits::is_simd_vector<type_decayed>::value,
                                  typename type_decayed::EntryType, float>::type,
        type_decayed::Size / Pieces>;

    type data;

    static constexpr std::size_t EntryOffset = Index * type_decayed::Size / Pieces;

    // no non-const operator[] needed
    decltype(std::declval<const type &>()[0]) operator[](size_t i) const { return data[i + EntryOffset]; }

    simd_array_type asSimdArray() const
    {
        return simd_cast<simd_array_type, Index>(data);
    }
};/*}}}*/

//Segment<T *, ...> specialization {{{
template <typename T_, std::size_t Pieces_, std::size_t Index_>
struct Segment<T_ *, Pieces_, Index_> {
    static_assert(Index_ < Pieces_, "You found a bug in Vc. Please report.");

    using type = T_ *;
    using type_decayed = typename std::decay<T_>::type;
    static constexpr size_t Pieces = Pieces_;
    static constexpr size_t Index = Index_;
    using simd_array_type = SimdArray<
        typename std::conditional<Traits::is_simd_vector<type_decayed>::value,
                                  typename type_decayed::VectorEntryType, float>::type,
        type_decayed::Size / Pieces> *;

    type data;

    static constexpr std::size_t EntryOffset = Index * type_decayed::size() / Pieces;

    simd_array_type asSimdArray() const
    {
        return reinterpret_cast<
#ifdef Vc_GCC
                   // GCC might ICE if this type is declared with may_alias. If it doesn't
                   // ICE it warns about ignoring the attribute.
                   typename std::remove_pointer<simd_array_type>::type
#else
                   MayAlias<typename std::remove_pointer<simd_array_type>::type>
#endif
                       *>(data) +
               Index;
    }

    //decltype(std::declval<type>()[0]) operator[](size_t i) { return data[i + EntryOffset]; }
    //decltype(std::declval<type>()[0]) operator[](size_t i) const { return data[i + EntryOffset]; }
};/*}}}*/

template <typename T, std::size_t Offset> struct AddOffset
{
    constexpr AddOffset() = default;
};

// class Split {{{1
template <std::size_t secondOffset> class Split
{
    // split (only for high part) generator functions
    template <class G>
    struct GeneratorOffset {
        G gen;
        Vc_INTRINSIC decltype(gen(std::size_t())) operator()(std::size_t i)
        {
            return gen(i + secondOffset);
        }
    };
    template <class G, class = decltype(std::declval<G>()(std::size_t())),
              class = typename std::enable_if<!Traits::is_simd_vector<G>::value>::type>
    static Vc_INTRINSIC GeneratorOffset<G> hiImpl(G &&gen)
    {
        return {std::forward<G>(gen)};
    }

    // split (only for high part) IndexesFromZero
    static Vc_INTRINSIC AddOffset<VectorSpecialInitializerIndexesFromZero, secondOffset>
        hiImpl(VectorSpecialInitializerIndexesFromZero)
    {
        return {};
    }
    template <std::size_t Offset>
    static Vc_INTRINSIC
        AddOffset<VectorSpecialInitializerIndexesFromZero, Offset + secondOffset>
            hiImpl(AddOffset<VectorSpecialInitializerIndexesFromZero, Offset>)
    {
        return {};
    }

    // split composite SimdArray
    template <typename U, std::size_t N, typename V, std::size_t M,
              typename = enable_if<N != M>>
    static Vc_INTRINSIC auto loImpl(const SimdArray<U, N, V, M> &x)
        -> decltype(internal_data0(x))
    {
        return internal_data0(x);
    }
    template <typename U, std::size_t N, typename V, std::size_t M,
              typename = enable_if<N != M>>
    static Vc_INTRINSIC auto hiImpl(const SimdArray<U, N, V, M> &x)
        -> decltype(internal_data1(x))
    {
        return internal_data1(x);
    }
    template <typename U, std::size_t N, typename V, std::size_t M,
              typename = enable_if<N != M>>
    static Vc_INTRINSIC auto loImpl(SimdArray<U, N, V, M> *x)
        -> decltype(&internal_data0(*x))
    {
        return &internal_data0(*x);
    }
    template <typename U, std::size_t N, typename V, std::size_t M,
              typename = enable_if<N != M>>
    static Vc_INTRINSIC auto hiImpl(SimdArray<U, N, V, M> *x)
        -> decltype(&internal_data1(*x))
    {
        return &internal_data1(*x);
    }

    // split atomic SimdArray
    template <typename U, std::size_t N, typename V>
    static Vc_INTRINSIC Segment<V, 2, 0> loImpl(const SimdArray<U, N, V, N> &x)
    {
        return {internal_data(x)};
    }
    template <typename U, std::size_t N, typename V>
    static Vc_INTRINSIC Segment<V, 2, 1> hiImpl(const SimdArray<U, N, V, N> &x)
    {
        return {internal_data(x)};
    }
    template <typename U, std::size_t N, typename V>
    static Vc_INTRINSIC Segment<V *, 2, 0> loImpl(SimdArray<U, N, V, N> *x)
    {
        return {&internal_data(*x)};
    }
    template <typename U, std::size_t N, typename V>
    static Vc_INTRINSIC Segment<V *, 2, 1> hiImpl(SimdArray<U, N, V, N> *x)
    {
        return {&internal_data(*x)};
    }

    // split composite SimdMaskArray
    template <typename U, std::size_t N, typename V, std::size_t M>
    static Vc_INTRINSIC auto loImpl(const SimdMaskArray<U, N, V, M> &x) -> decltype(internal_data0(x))
    {
        return internal_data0(x);
    }
    template <typename U, std::size_t N, typename V, std::size_t M>
    static Vc_INTRINSIC auto hiImpl(const SimdMaskArray<U, N, V, M> &x) -> decltype(internal_data1(x))
    {
        return internal_data1(x);
    }

    template <typename U, std::size_t N, typename V>
    static Vc_INTRINSIC Segment<typename SimdMaskArray<U, N, V, N>::mask_type, 2, 0> loImpl(
        const SimdMaskArray<U, N, V, N> &x)
    {
        return {internal_data(x)};
    }
    template <typename U, std::size_t N, typename V>
    static Vc_INTRINSIC Segment<typename SimdMaskArray<U, N, V, N>::mask_type, 2, 1> hiImpl(
        const SimdMaskArray<U, N, V, N> &x)
    {
        return {internal_data(x)};
    }

    // split Vector<T> and Mask<T>
    template <typename T>
    static constexpr bool is_vector_or_mask(){
        return (Traits::is_simd_vector<T>::value && !Traits::isSimdArray<T>::value) ||
               (Traits::is_simd_mask<T>::value && !Traits::isSimdMaskArray<T>::value);
    }
    template <typename V>
    static Vc_INTRINSIC Segment<V, 2, 0> loImpl(V &&x, enable_if<is_vector_or_mask<V>()> = nullarg)
    {
        return {std::forward<V>(x)};
    }
    template <typename V>
    static Vc_INTRINSIC Segment<V, 2, 1> hiImpl(V &&x, enable_if<is_vector_or_mask<V>()> = nullarg)
    {
        return {std::forward<V>(x)};
    }

    // generically split Segments
    template <typename V, std::size_t Pieces, std::size_t Index>
    static Vc_INTRINSIC Segment<V, 2 * Pieces, 2 * Index> loImpl(
        const Segment<V, Pieces, Index> &x)
    {
        return {x.data};
    }
    template <typename V, std::size_t Pieces, std::size_t Index>
    static Vc_INTRINSIC Segment<V, 2 * Pieces, 2 * Index + 1> hiImpl(
        const Segment<V, Pieces, Index> &x)
    {
        return {x.data};
    }

    template <typename T, typename = decltype(loImpl(std::declval<T>()))>
    static std::true_type have_lo_impl(int);
    template <typename T> static std::false_type have_lo_impl(float);
    template <typename T> static constexpr bool have_lo_impl()
    {
        return decltype(have_lo_impl<T>(1))::value;
    }

    template <typename T, typename = decltype(hiImpl(std::declval<T>()))>
    static std::true_type have_hi_impl(int);
    template <typename T> static std::false_type have_hi_impl(float);
    template <typename T> static constexpr bool have_hi_impl()
    {
        return decltype(have_hi_impl<T>(1))::value;
    }

public:
    template <typename U>
    static Vc_INTRINSIC const U *lo(Operations::gather, const U *ptr)
    {
        return ptr;
    }
    template <typename U>
    static Vc_INTRINSIC const U *hi(Operations::gather, const U *ptr)
    {
        return ptr + secondOffset;
    }
    template <typename U, typename = enable_if<!std::is_pointer<U>::value>>
    static Vc_ALWAYS_INLINE decltype(loImpl(std::declval<U>()))
        lo(Operations::gather, U &&x)
    {
        return loImpl(std::forward<U>(x));
    }
    template <typename U, typename = enable_if<!std::is_pointer<U>::value>>
    static Vc_ALWAYS_INLINE decltype(hiImpl(std::declval<U>()))
        hi(Operations::gather, U &&x)
    {
        return hiImpl(std::forward<U>(x));
    }
    template <typename U>
    static Vc_INTRINSIC const U *lo(Operations::scatter, const U *ptr)
    {
        return ptr;
    }
    template <typename U>
    static Vc_INTRINSIC const U *hi(Operations::scatter, const U *ptr)
    {
        return ptr + secondOffset;
    }

    template <typename U>
    static Vc_ALWAYS_INLINE decltype(loImpl(std::declval<U>())) lo(U &&x)
    {
        return loImpl(std::forward<U>(x));
    }
    template <typename U>
    static Vc_ALWAYS_INLINE decltype(hiImpl(std::declval<U>())) hi(U &&x)
    {
        return hiImpl(std::forward<U>(x));
    }

    template <typename U>
    static Vc_ALWAYS_INLINE enable_if<!have_lo_impl<U>(), U> lo(U &&x)
    {
        return std::forward<U>(x);
    }
    template <typename U>
    static Vc_ALWAYS_INLINE enable_if<!have_hi_impl<U>(), U> hi(U &&x)
    {
        return std::forward<U>(x);
    }
};

// actual_value {{{1
template <typename Op, typename U, std::size_t M, typename V>
static Vc_INTRINSIC const V &actual_value(Op, const SimdArray<U, M, V, M> &x)
{
  return internal_data(x);
}
template <typename Op, typename U, std::size_t M, typename V>
static Vc_INTRINSIC V *actual_value(Op, SimdArray<U, M, V, M> *x)
{
  return &internal_data(*x);
}
template <typename Op, typename T, size_t Pieces, size_t Index>
static Vc_INTRINSIC typename Segment<T, Pieces, Index>::simd_array_type actual_value(
    Op, Segment<T, Pieces, Index> &&seg)
{
    return seg.asSimdArray();
}

template <typename Op, typename U, std::size_t M, typename V>
static Vc_INTRINSIC const typename V::Mask &actual_value(Op, const SimdMaskArray<U, M, V, M> &x)
{
  return internal_data(x);
}
template <typename Op, typename U, std::size_t M, typename V>
static Vc_INTRINSIC typename V::Mask *actual_value(Op, SimdMaskArray<U, M, V, M> *x)
{
  return &internal_data(*x);
}

// unpackArgumentsAuto {{{1

template <typename Op, typename Arg>
Vc_INTRINSIC decltype(actual_value(std::declval<Op &>(), std::declval<Arg>()))
conditionalUnpack(std::true_type, Op op, Arg &&arg)
{
    return actual_value(op, std::forward<Arg>(arg));
}
template <typename Op, typename Arg>
Vc_INTRINSIC Arg conditionalUnpack(std::false_type, Op, Arg &&arg)
{
    return std::forward<Arg>(arg);
}

template <size_t A, size_t B>
struct selectorType : public std::integral_constant<bool, !((A & (size_t(1) << B)) != 0)> {
};

template <size_t I, typename Op, typename R, typename... Args, size_t... Indexes>
Vc_INTRINSIC decltype(std::declval<Op &>()(std::declval<R &>(),
                                           conditionalUnpack(selectorType<I, Indexes>(),
                                                             std::declval<Op &>(),
                                                             std::declval<Args>())...))
unpackArgumentsAutoImpl(int, index_sequence<Indexes...>, Op op, R &&r, Args &&... args)
{
    op(std::forward<R>(r),
       conditionalUnpack(selectorType<I, Indexes>(), op, std::forward<Args>(args))...);
}

template <size_t I, typename Op, typename R, typename... Args, size_t... Indexes>
Vc_INTRINSIC enable_if<(I <= (size_t(1) << sizeof...(Args))), void> unpackArgumentsAutoImpl(
    float, index_sequence<Indexes...> is, Op op, R &&r, Args &&... args)
{
    // if R is nullptr_t then the return type cannot enforce that actually any unwrapping
    // of the SimdArray types happens. Thus, you could get an endless loop of the
    // SimdArray function overload calling itself, if the index goes up to (1 <<
    // sizeof...(Args)) - 1 (which means no argument transformations via actual_value).
    static_assert(
        I < (1 << sizeof...(Args)) - (std::is_same<R, std::nullptr_t>::value ? 1 : 0),
        "Vc or compiler bug. Please report. Failed to find a combination of "
        "actual_value(arg) transformations that allows calling Op.");
    unpackArgumentsAutoImpl<I + 1, Op, R, Args...>(int(), is, op, std::forward<R>(r),
                                                   std::forward<Args>(args)...);
}

#ifdef Vc_ICC
template <size_t, typename... Ts> struct IccWorkaround {
    using type = void;
};
template <typename... Ts> struct IccWorkaround<2, Ts...> {
    using type = typename std::remove_pointer<typename std::decay<
        typename std::tuple_element<1, std::tuple<Ts...>>::type>::type>::type;
};
#endif

template <typename Op, typename R, typename... Args>
Vc_INTRINSIC void unpackArgumentsAuto(Op op, R &&r, Args &&... args)
{
#ifdef Vc_ICC
    // ugly hacky workaround for ICC:
    // The compiler fails to do SFINAE right on recursion. We have to hit the right
    // recursionStart number from the start.
    const int recursionStart =
        Traits::isSimdArray<
            typename IccWorkaround<sizeof...(Args), Args...>::type>::value &&
                (std::is_same<Op, Common::Operations::Forward_frexp>::value ||
                 std::is_same<Op, Common::Operations::Forward_ldexp>::value)
            ? 2
            : 0;
#else
    const int recursionStart = 0;
#endif
    unpackArgumentsAutoImpl<recursionStart>(
        int(), make_index_sequence<sizeof...(Args)>(), op, std::forward<R>(r),
        std::forward<Args>(args)...);
}

//}}}1
}  // namespace Common
}  // namespace Vc

#endif  // VC_COMMON_SIMDARRAYHELPER_H_

// vim: foldmethod=marker