x86_prefetches.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_X86_PREFETCHES_H_
#define VC_COMMON_X86_PREFETCHES_H_

#include <xmmintrin.h>
#include "macros.h"

namespace Vc_VERSIONED_NAMESPACE
{
namespace Common
{

#if defined(Vc_IMPL_MIC)
static constexpr int exclusive_hint = 0x4;
#else
static constexpr int exclusive_hint = 0;
#endif

// TODO: support AMD's prefetchw with correct flags and checks via cpuid

template <typename ExclusiveOrShared = Vc::Shared>
Vc_INTRINSIC void prefetchForOneRead(const void *addr)
{
    if (std::is_same<ExclusiveOrShared, Vc::Shared>::value) {
        _mm_prefetch(static_cast<char *>(const_cast<void *>(addr)), _MM_HINT_NTA);
    } else {
        _mm_prefetch(static_cast<char *>(const_cast<void *>(addr)),
                     static_cast<decltype(_MM_HINT_NTA)>(_MM_HINT_NTA | exclusive_hint));
    }
}
template <typename ExclusiveOrShared = Vc::Shared>
Vc_INTRINSIC void prefetchClose(const void *addr)
{
    if (std::is_same<ExclusiveOrShared, Vc::Shared>::value) {
        _mm_prefetch(static_cast<char *>(const_cast<void *>(addr)), _MM_HINT_T0);
    } else {
        _mm_prefetch(static_cast<char *>(const_cast<void *>(addr)),
                     static_cast<decltype(_MM_HINT_T0)>(_MM_HINT_T0 | exclusive_hint));
    }
}
template <typename ExclusiveOrShared = Vc::Shared>
Vc_INTRINSIC void prefetchMid(const void *addr)
{
    if (std::is_same<ExclusiveOrShared, Vc::Shared>::value) {
        _mm_prefetch(static_cast<char *>(const_cast<void *>(addr)), _MM_HINT_T1);
    } else {
        _mm_prefetch(static_cast<char *>(const_cast<void *>(addr)),
                     static_cast<decltype(_MM_HINT_T1)>(_MM_HINT_T1 | exclusive_hint));
    }
}
template <typename ExclusiveOrShared = Vc::Shared>
Vc_INTRINSIC void prefetchFar(const void *addr)
{
    if (std::is_same<ExclusiveOrShared, Vc::Shared>::value) {
        _mm_prefetch(static_cast<char *>(const_cast<void *>(addr)), _MM_HINT_T2);
    } else {
        _mm_prefetch(static_cast<char *>(const_cast<void *>(addr)),
                     static_cast<decltype(_MM_HINT_T2)>(_MM_HINT_T2 | exclusive_hint));
    }
}

/*handlePrefetch/handleLoadPrefetches/handleStorePrefetches{{{*/
namespace
{
template<size_t L1, size_t L2, bool UseExclusivePrefetch> Vc_INTRINSIC void handlePrefetch(const void *addr_, typename std::enable_if<L1 != 0 && L2 != 0, void *>::type = nullptr)
{
    const char *addr = static_cast<const char *>(addr_);
    prefetchClose<typename std::conditional<UseExclusivePrefetch, Vc::Exclusive, Vc::Shared>::type>(addr + L1);
    prefetchMid  <typename std::conditional<UseExclusivePrefetch, Vc::Exclusive, Vc::Shared>::type>(addr + L2);
}
template<size_t L1, size_t L2, bool UseExclusivePrefetch> Vc_INTRINSIC void handlePrefetch(const void *addr_, typename std::enable_if<L1 == 0 && L2 != 0, void *>::type = nullptr)
{
    const char *addr = static_cast<const char *>(addr_);
    prefetchMid  <typename std::conditional<UseExclusivePrefetch, Vc::Exclusive, Vc::Shared>::type>(addr + L2);
}
template<size_t L1, size_t L2, bool UseExclusivePrefetch> Vc_INTRINSIC void handlePrefetch(const void *addr_, typename std::enable_if<L1 != 0 && L2 == 0, void *>::type = nullptr)
{
    const char *addr = static_cast<const char *>(addr_);
    prefetchClose<typename std::conditional<UseExclusivePrefetch, Vc::Exclusive, Vc::Shared>::type>(addr + L1);
}
template<size_t L1, size_t L2, bool UseExclusivePrefetch> Vc_INTRINSIC void handlePrefetch(const void *, typename std::enable_if<L1 == 0 && L2 == 0, void *>::type = nullptr)
{
}

template<typename Flags> Vc_INTRINSIC void handleLoadPrefetches(const void *    , Flags, typename Flags::EnableIfNotPrefetch = nullptr) {}
template<typename Flags> Vc_INTRINSIC void handleLoadPrefetches(const void *addr, Flags, typename Flags::EnableIfPrefetch    = nullptr)
{
    // load prefetches default to Shared unless Exclusive was explicitely selected
    handlePrefetch<Flags::L1Stride, Flags::L2Stride, Flags::IsExclusivePrefetch>(addr);
}

template<typename Flags> Vc_INTRINSIC void handleStorePrefetches(const void *    , Flags, typename Flags::EnableIfNotPrefetch = nullptr) {}
template<typename Flags> Vc_INTRINSIC void handleStorePrefetches(const void *addr, Flags, typename Flags::EnableIfPrefetch    = nullptr)
{
    // store prefetches default to Exclusive unless Shared was explicitely selected
    handlePrefetch<Flags::L1Stride, Flags::L2Stride, !Flags::IsSharedPrefetch>(addr);
}

} // anonymous namespace
/*}}}*/

}  // namespace Common

using Common::prefetchForOneRead;
using Common::prefetchClose;
using Common::prefetchMid;
using Common::prefetchFar;
}  // namespace Vc

#endif // VC_COMMON_X86_PREFETCHES_H_

// vim: foldmethod=marker