Eigen/src/Core/util/Memory.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008 Gael Guennebaud <g.gael@free.fr>
// Copyright (C) 2008-2009 Benoit Jacob <jacob.benoit.1@gmail.com>
// Copyright (C) 2009 Kenneth Riddile <kfriddile@yahoo.com>
//
// Eigen is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// Alternatively, 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 2 of
// the License, or (at your option) any later version.
//
// Eigen 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 Lesser General Public License or the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License and a copy of the GNU General Public License along with
// Eigen. If not, see <http://www.gnu.org/licenses/>.

#ifndef EIGEN_MEMORY_H
#define EIGEN_MEMORY_H

// FreeBSD 6 seems to have 16-byte aligned malloc
// See http://svn.freebsd.org/viewvc/base/stable/6/lib/libc/stdlib/malloc.c?view=markup
// FreeBSD 7 seems to have 16-byte aligned malloc except on ARM and MIPS architectures
// See http://svn.freebsd.org/viewvc/base/stable/7/lib/libc/stdlib/malloc.c?view=markup
#if defined(__FreeBSD__) && !defined(__arm__) && !defined(__mips__)
#define EIGEN_FREEBSD_MALLOC_ALREADY_ALIGNED 1
#else
#define EIGEN_FREEBSD_MALLOC_ALREADY_ALIGNED 0
#endif

#if defined(__APPLE__) || defined(_WIN64) || EIGEN_FREEBSD_MALLOC_ALREADY_ALIGNED
  #define EIGEN_MALLOC_ALREADY_ALIGNED 1
#else
  #define EIGEN_MALLOC_ALREADY_ALIGNED 0
#endif

#if ((defined _GNU_SOURCE) || ((defined _XOPEN_SOURCE) && (_XOPEN_SOURCE >= 600))) && (defined _POSIX_ADVISORY_INFO) && (_POSIX_ADVISORY_INFO > 0)
  #define EIGEN_HAS_POSIX_MEMALIGN 1
#else
  #define EIGEN_HAS_POSIX_MEMALIGN 0
#endif

#ifdef EIGEN_VECTORIZE_SSE
  #define EIGEN_HAS_MM_MALLOC 1
#else
  #define EIGEN_HAS_MM_MALLOC 0
#endif

/** \internal like malloc, but the returned pointer is guaranteed to be 16-byte aligned.
  * Fast, but wastes 16 additional bytes of memory.
  * Does not throw any exception.
  */
inline void* ei_handmade_aligned_malloc(size_t size)
{
  void *original = malloc(size+16);
  void *aligned = reinterpret_cast<void*>((reinterpret_cast<size_t>(original) & ~(size_t(15))) + 16);
  *(reinterpret_cast<void**>(aligned) - 1) = original;
  return aligned;
}

/** \internal frees memory allocated with ei_handmade_aligned_malloc */
inline void ei_handmade_aligned_free(void *ptr)
{
  if(ptr)
    free(*(reinterpret_cast<void**>(ptr) - 1));
}

/** \internal allocates \a size bytes. The returned pointer is guaranteed to have 16 bytes alignment.
  * On allocation error, the returned pointer is null, and if exceptions are enabled then a std::bad_alloc is thrown.
  */
inline void* ei_aligned_malloc(size_t size)
{
  #ifdef EIGEN_NO_MALLOC
    ei_assert(false && "heap allocation is forbidden (EIGEN_NO_MALLOC is defined)");
  #endif

  void *result;
  #if !EIGEN_ALIGN
    result = malloc(size);
  #elif EIGEN_MALLOC_ALREADY_ALIGNED
    result = malloc(size);
  #elif EIGEN_HAS_POSIX_MEMALIGN
    if(posix_memalign(&result, 16, size)) result = 0;
  #elif EIGEN_HAS_MM_MALLOC
    result = _mm_malloc(size, 16);
  #elif (defined _MSC_VER)
    result = _aligned_malloc(size, 16);
  #else
    result = ei_handmade_aligned_malloc(size);
  #endif

  #ifdef EIGEN_EXCEPTIONS
    if(result == 0)
      throw std::bad_alloc();
  #endif
  return result;
}

/** allocates \a size bytes. If Align is true, then the returned ptr is 16-byte-aligned.
  * On allocation error, the returned pointer is null, and if exceptions are enabled then a std::bad_alloc is thrown.
  */
template<bool Align> inline void* ei_conditional_aligned_malloc(size_t size)
{
  return ei_aligned_malloc(size);
}

template<> inline void* ei_conditional_aligned_malloc<false>(size_t size)
{
  #ifdef EIGEN_NO_MALLOC
    ei_assert(false && "heap allocation is forbidden (EIGEN_NO_MALLOC is defined)");
  #endif

  void *result = malloc(size);
  #ifdef EIGEN_EXCEPTIONS
    if(!result) throw std::bad_alloc();
  #endif
  return result;
}

/** \internal construct the elements of an array.
  * The \a size parameter tells on how many objects to call the constructor of T.
  */
template<typename T> inline T* ei_construct_elements_of_array(T *ptr, size_t size)
{
  for (size_t i=0; i < size; ++i) ::new (ptr + i) T;
  return ptr;
}

/** allocates \a size objects of type T. The returned pointer is guaranteed to have 16 bytes alignment.
  * On allocation error, the returned pointer is undefined, but if exceptions are enabled then a std::bad_alloc is thrown.
  * The default constructor of T is called.
  */
template<typename T> inline T* ei_aligned_new(size_t size)
{
  T *result = reinterpret_cast<T*>(ei_aligned_malloc(sizeof(T)*size));
  return ei_construct_elements_of_array(result, size);
}

template<typename T, bool Align> inline T* ei_conditional_aligned_new(size_t size)
{
  T *result = reinterpret_cast<T*>(ei_conditional_aligned_malloc<Align>(sizeof(T)*size));
  return ei_construct_elements_of_array(result, size);
}

/** \internal free memory allocated with ei_aligned_malloc
  */
inline void ei_aligned_free(void *ptr)
{
  #if !EIGEN_ALIGN
    free(ptr);
  #elif EIGEN_MALLOC_ALREADY_ALIGNED
    free(ptr);
  #elif EIGEN_HAS_POSIX_MEMALIGN
    free(ptr);
  #elif EIGEN_HAS_MM_MALLOC
    _mm_free(ptr);
  #elif defined(_MSC_VER)
    _aligned_free(ptr);
  #else
    ei_handmade_aligned_free(ptr);
  #endif
}

/** \internal free memory allocated with ei_conditional_aligned_malloc
  */
template<bool Align> inline void ei_conditional_aligned_free(void *ptr)
{
  ei_aligned_free(ptr);
}

template<> inline void ei_conditional_aligned_free<false>(void *ptr)
{
  free(ptr);
}

/** \internal destruct the elements of an array.
  * The \a size parameters tells on how many objects to call the destructor of T.
  */
template<typename T> inline void ei_destruct_elements_of_array(T *ptr, size_t size)
{
  // always destruct an array starting from the end.
  while(size) ptr[--size].~T();
}

/** \internal delete objects constructed with ei_aligned_new
  * The \a size parameters tells on how many objects to call the destructor of T.
  */
template<typename T> inline void ei_aligned_delete(T *ptr, size_t size)
{
  ei_destruct_elements_of_array<T>(ptr, size);
  ei_aligned_free(ptr);
}

/** \internal delete objects constructed with ei_conditional_aligned_new
  * The \a size parameters tells on how many objects to call the destructor of T.
  */
template<typename T, bool Align> inline void ei_conditional_aligned_delete(T *ptr, size_t size)
{
  ei_destruct_elements_of_array<T>(ptr, size);
  ei_conditional_aligned_free<Align>(ptr);
}

/** \internal \returns the index of the first element of the array that is well aligned for vectorization.
  *
  * \param array the address of the start of the array
  * \param size the size of the array
  *
  * \note If no element of the array is well aligned, the size of the array is returned. Typically,
  * for example with SSE, "well aligned" means 16-byte-aligned. If vectorization is disabled or if the
  * packet size for the given scalar type is 1, then everything is considered well-aligned.
  *
  * \note If the scalar type is vectorizable, we rely on the following assumptions: sizeof(Scalar) is a
  * power of 2, the packet size in bytes is also a power of 2, and is a multiple of sizeof(Scalar). On the
  * other hand, we do not assume that the array address is a multiple of sizeof(Scalar), as that fails for
  * example with Scalar=double on certain 32-bit platforms, see bug #79.
  *
  * There is also the variant ei_first_aligned(const MatrixBase&, Integer) defined in Coeffs.h.
  */
template<typename Scalar, typename Integer>
inline static Integer ei_first_aligned(const Scalar* array, Integer size)
{
  typedef typename ei_packet_traits<Scalar>::type Packet;
  enum { PacketSize = ei_packet_traits<Scalar>::size,
         PacketAlignedMask = PacketSize-1
  };
  
  if(PacketSize==1)
  {
    // Either there is no vectorization, or a packet consists of exactly 1 scalar so that all elements
    // of the array have the same aligment.
    return 0;
  }
  else if(size_t(array) & (sizeof(Scalar)-1))
  {
    // There is vectorization for this scalar type, but the array is not aligned to the size of a single scalar.
    // Consequently, no element of the array is well aligned.
    return size;
  }
  else
  {
    return std::min<Integer>( (PacketSize - (Integer((size_t(array)/sizeof(Scalar))) & PacketAlignedMask))
                           & PacketAlignedMask, size);
  }
}

/** \internal
  * ei_aligned_stack_alloc(SIZE) allocates an aligned buffer of SIZE bytes
  * on the stack if SIZE is smaller than EIGEN_STACK_ALLOCATION_LIMIT, and
  * if stack allocation is supported by the platform (currently, this is linux only).
  * Otherwise the memory is allocated on the heap.
  * Data allocated with ei_aligned_stack_alloc \b must be freed by calling ei_aligned_stack_free(PTR,SIZE).
  * \code
  * float * data = ei_aligned_stack_alloc(float,array.size());
  * // ...
  * ei_aligned_stack_free(data,float,array.size());
  * \endcode
  */
#ifdef __linux__
  #define ei_aligned_stack_alloc(SIZE) (SIZE<=EIGEN_STACK_ALLOCATION_LIMIT) \
                                    ? alloca(SIZE) \
                                    : ei_aligned_malloc(SIZE)
  #define ei_aligned_stack_free(PTR,SIZE) if(SIZE>EIGEN_STACK_ALLOCATION_LIMIT) ei_aligned_free(PTR)
#else
  #define ei_aligned_stack_alloc(SIZE) ei_aligned_malloc(SIZE)
  #define ei_aligned_stack_free(PTR,SIZE) ei_aligned_free(PTR)
#endif

#define ei_aligned_stack_new(TYPE,SIZE) ei_construct_elements_of_array(reinterpret_cast<TYPE*>(ei_aligned_stack_alloc(sizeof(TYPE)*SIZE)), SIZE)
#define ei_aligned_stack_delete(TYPE,PTR,SIZE) do {ei_destruct_elements_of_array<TYPE>(PTR, SIZE); \
                                                   ei_aligned_stack_free(PTR,sizeof(TYPE)*SIZE);} while(0)


#if EIGEN_ALIGN
  #ifdef EIGEN_EXCEPTIONS
    #define EIGEN_MAKE_ALIGNED_OPERATOR_NEW_NOTHROW(NeedsToAlign) \
      void* operator new(size_t size, const std::nothrow_t&) throw() { \
        try { return Eigen::ei_conditional_aligned_malloc<NeedsToAlign>(size); } \
        catch (...) { return 0; } \
        return 0; \
      }
  #else
    #define EIGEN_MAKE_ALIGNED_OPERATOR_NEW_NOTHROW(NeedsToAlign) \
      void* operator new(size_t size, const std::nothrow_t&) throw() { \
        return Eigen::ei_conditional_aligned_malloc<NeedsToAlign>(size); \
      }
  #endif

  #define EIGEN_MAKE_ALIGNED_OPERATOR_NEW_IF(NeedsToAlign) \
      void *operator new(size_t size) { \
        return Eigen::ei_conditional_aligned_malloc<NeedsToAlign>(size); \
      } \
      void *operator new[](size_t size) { \
        return Eigen::ei_conditional_aligned_malloc<NeedsToAlign>(size); \
      } \
      void operator delete(void * ptr) throw() { Eigen::ei_conditional_aligned_free<NeedsToAlign>(ptr); } \
      void operator delete[](void * ptr) throw() { Eigen::ei_conditional_aligned_free<NeedsToAlign>(ptr); } \
      /* in-place new and delete. since (at least afaik) there is no actual   */ \
      /* memory allocated we can safely let the default implementation handle */ \
      /* this particular case. */ \
      static void *operator new(size_t size, void *ptr) { return ::operator new(size,ptr); } \
      void operator delete(void * memory, void *ptr) throw() { return ::operator delete(memory,ptr); } \
      /* nothrow-new (returns zero instead of std::bad_alloc) */ \
      EIGEN_MAKE_ALIGNED_OPERATOR_NEW_NOTHROW(NeedsToAlign) \
      void operator delete(void *ptr, const std::nothrow_t&) throw() { \
        Eigen::ei_conditional_aligned_free<NeedsToAlign>(ptr); \
      } \
      typedef void ei_operator_new_marker_type;
#else
  #define EIGEN_MAKE_ALIGNED_OPERATOR_NEW_IF(NeedsToAlign)
#endif

#define EIGEN_MAKE_ALIGNED_OPERATOR_NEW EIGEN_MAKE_ALIGNED_OPERATOR_NEW_IF(true)
#define EIGEN_MAKE_ALIGNED_OPERATOR_NEW_IF_VECTORIZABLE_FIXED_SIZE(Scalar,Size) \
  EIGEN_MAKE_ALIGNED_OPERATOR_NEW_IF(((Size)!=Eigen::Dynamic) && ((sizeof(Scalar)*(Size))%16==0))


/** \class aligned_allocator
*
* \brief stl compatible allocator to use with with 16 byte aligned types
*
* Example:
* \code
* // Matrix4f requires 16 bytes alignment:
* std::map< int, Matrix4f, std::less<int>, aligned_allocator<Matrix4f> > my_map_mat4;
* // Vector3f does not require 16 bytes alignment, no need to use Eigen's allocator:
* std::map< int, Vector3f > my_map_vec3;
* \endcode
*
*/
template<class T>
class aligned_allocator
{
public:
    typedef size_t    size_type;
    typedef ptrdiff_t difference_type;
    typedef T*        pointer;
    typedef const T*  const_pointer;
    typedef T&        reference;
    typedef const T&  const_reference;
    typedef T         value_type;

    template<class U>
    struct rebind
    {
        typedef aligned_allocator<U> other;
    };

    pointer address( reference value ) const
    {
        return &value;
    }

    const_pointer address( const_reference value ) const
    {
        return &value;
    }

    aligned_allocator() throw()
    {
    }

    aligned_allocator( const aligned_allocator& ) throw()
    {
    }

    template<class U>
    aligned_allocator( const aligned_allocator<U>& ) throw()
    {
    }

    ~aligned_allocator() throw()
    {
    }

    size_type max_size() const throw()
    {
        return std::numeric_limits<size_type>::max();
    }

    pointer allocate( size_type num, const_pointer* hint = 0 )
    {
        static_cast<void>( hint ); // suppress unused variable warning
        return static_cast<pointer>( ei_aligned_malloc( num * sizeof(T) ) );
    }

    void construct( pointer p, const T& value )
    {
        ::new( p ) T( value );
    }

    void destroy( pointer p )
    {
        p->~T();
    }

    void deallocate( pointer p, size_type /*num*/ )
    {
        ei_aligned_free( p );
    }

    bool operator!=(const aligned_allocator<T>& ) const
    { return false; }

    bool operator==(const aligned_allocator<T>& ) const
    { return true; }
};

#endif // EIGEN_MEMORY_H