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/***************************************************************************
* Copyright (c) Johan Mabille, Sylvain Corlay, Wolf Vollprecht and *
* Martin Renou *
* Copyright (c) QuantStack *
* Copyright (c) Serge Guelton *
* *
* Distributed under the terms of the BSD 3-Clause License. *
* *
* The full license is in the file LICENSE, distributed with this software. *
****************************************************************************/
#ifndef XSIMD_ARCH_HPP
#define XSIMD_ARCH_HPP
#include <initializer_list>
#include <type_traits>
#include <utility>
#include "../types/xsimd_all_registers.hpp"
#include "./xsimd_config.hpp"
#include "./xsimd_cpuid.hpp"
namespace xsimd
{
namespace detail
{
// Checks whether T appears in Tys.
template <class T, class... Tys>
struct contains;
template <class T>
struct contains<T> : std::false_type
{
};
template <class T, class Ty, class... Tys>
struct contains<T, Ty, Tys...>
: std::conditional<std::is_same<Ty, T>::value, std::true_type,
contains<T, Tys...>>::type
{
};
template <class... Archs>
struct is_sorted;
template <>
struct is_sorted<> : std::true_type
{
};
template <class Arch>
struct is_sorted<Arch> : std::true_type
{
};
template <class A0, class A1, class... Archs>
struct is_sorted<A0, A1, Archs...>
: std::conditional<(A0::version() >= A1::version()), is_sorted<Archs...>,
std::false_type>::type
{
};
template <typename T>
inline constexpr T max_of(T value) noexcept
{
return value;
}
template <typename T, typename... Ts>
inline constexpr T max_of(T head0, T head1, Ts... tail) noexcept
{
return max_of((head0 > head1 ? head0 : head1), tail...);
}
} // namespace detail
// An arch_list is a list of architectures, sorted by version number.
template <class... Archs>
struct arch_list
{
#ifndef NDEBUG
static_assert(detail::is_sorted<Archs...>::value,
"architecture list must be sorted by version");
#endif
template <class Arch>
using add = arch_list<Archs..., Arch>;
template <class... OtherArchs>
using extend = arch_list<Archs..., OtherArchs...>;
template <class Arch>
static constexpr bool contains() noexcept
{
return detail::contains<Arch, Archs...>::value;
}
template <class F>
static void for_each(F&& f) noexcept
{
(void)std::initializer_list<bool> { (f(Archs {}), true)... };
}
static constexpr std::size_t alignment() noexcept
{
// all alignments are a power of two
return detail::max_of(Archs::alignment()..., static_cast<size_t>(0));
}
};
struct unavailable
{
static constexpr bool supported() noexcept { return false; }
static constexpr bool available() noexcept { return false; }
static constexpr unsigned version() noexcept { return 0; }
static constexpr std::size_t alignment() noexcept { return 0; }
static constexpr bool requires_alignment() noexcept { return false; }
static constexpr char const* name() noexcept { return "<none>"; }
};
namespace detail
{
// Pick the best architecture in arch_list L, which is the last
// because architectures are sorted by version.
template <class L>
struct best;
template <>
struct best<arch_list<>>
{
using type = unavailable;
};
template <class Arch, class... Archs>
struct best<arch_list<Arch, Archs...>>
{
using type = Arch;
};
// Filter archlists Archs, picking only supported archs and adding
// them to L.
template <class L, class... Archs>
struct supported_helper;
template <class L>
struct supported_helper<L, arch_list<>>
{
using type = L;
};
template <class L, class Arch, class... Archs>
struct supported_helper<L, arch_list<Arch, Archs...>>
: supported_helper<
typename std::conditional<Arch::supported(),
typename L::template add<Arch>, L>::type,
arch_list<Archs...>>
{
};
template <class... Archs>
struct supported : supported_helper<arch_list<>, Archs...>
{
};
// Joins all arch_list Archs in a single arch_list.
template <class... Archs>
struct join;
template <class Arch>
struct join<Arch>
{
using type = Arch;
};
template <class Arch, class... Archs, class... Args>
struct join<Arch, arch_list<Archs...>, Args...>
: join<typename Arch::template extend<Archs...>, Args...>
{
};
} // namespace detail
struct unsupported
{
};
using all_x86_architectures = arch_list<avx512bw, avx512dq, avx512cd, avx512f, fma3<avx2>, avx2, fma3<avx>, avx, fma4, fma3<sse4_2>, sse4_2, sse4_1, /*sse4a,*/ ssse3, sse3, sse2>;
using all_sve_architectures = arch_list<detail::sve<512>, detail::sve<256>, detail::sve<128>>;
using all_arm_architectures = typename detail::join<all_sve_architectures, arch_list<neon64, neon>>::type;
using all_architectures = typename detail::join<all_arm_architectures, all_x86_architectures>::type;
using supported_architectures = typename detail::supported<all_architectures>::type;
using x86_arch = typename detail::best<typename detail::supported<all_x86_architectures>::type>::type;
using arm_arch = typename detail::best<typename detail::supported<all_arm_architectures>::type>::type;
// using default_arch = typename detail::best<typename detail::supported<arch_list</*arm_arch,*/ x86_arch>>::type>::type;
using default_arch = typename std::conditional<std::is_same<x86_arch, unavailable>::value,
arm_arch,
x86_arch>::type;
namespace detail
{
template <class F, class ArchList>
class dispatcher
{
const unsigned best_arch;
F functor;
template <class Arch, class... Tys>
auto walk_archs(arch_list<Arch>, Tys&&... args) noexcept -> decltype(functor(Arch {}, std::forward<Tys>(args)...))
{
assert(Arch::available() && "At least one arch must be supported during dispatch");
return functor(Arch {}, std::forward<Tys>(args)...);
}
template <class Arch, class ArchNext, class... Archs, class... Tys>
auto walk_archs(arch_list<Arch, ArchNext, Archs...>, Tys&&... args) noexcept -> decltype(functor(Arch {}, std::forward<Tys>(args)...))
{
if (Arch::version() <= best_arch)
return functor(Arch {}, std::forward<Tys>(args)...);
else
return walk_archs(arch_list<ArchNext, Archs...> {}, std::forward<Tys>(args)...);
}
public:
dispatcher(F f) noexcept
: best_arch(available_architectures().best)
, functor(f)
{
}
template <class... Tys>
auto operator()(Tys&&... args) noexcept -> decltype(functor(default_arch {}, std::forward<Tys>(args)...))
{
return walk_archs(ArchList {}, std::forward<Tys>(args)...);
}
};
}
// Generic function dispatch, à la ifunc
template <class ArchList = supported_architectures, class F>
inline detail::dispatcher<F, ArchList> dispatch(F&& f) noexcept
{
return { std::forward<F>(f) };
}
} // namespace xsimd
#endif
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