src/gromacs/simd/impl_reference/impl_reference_general.h

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  35
  36 #ifndef GMX_SIMD_IMPL_REFERENCE_GENERAL_H
  37 #define GMX_SIMD_IMPL_REFERENCE_GENERAL_H
  38
  39 #include "gromacs/utility/basedefinitions.h"
  40
  41 /*! \libinternal \file
  42  *
  43  * \brief Reference SIMD implementation, general utility functions
  44  *
  45  * \author Erik Lindahl <erik.lindahl@scilifelab.se>
  46  *
  47  * \ingroup module_simd
  48  */
  49
  50 namespace gmx
  51 {
  52
  53 /*! \brief Prefetch memory at address m
  54  *
  55  *  This typically prefetches one cache line of memory from address m,
  56  *  usually 64bytes or more, but the exact amount will depend on the
  57  *  implementation. On many platforms this is simply a no-op. Technically it
  58  *  might not be part of the SIMD instruction set, but since it is a
  59  *  hardware-specific function that is normally only used in tight loops where
  60  *  we also apply SIMD, it fits well here.
  61  *
  62  *  There are no guarantees about the level of cache or temporality, but
  63  *  usually we expect stuff to end up in level 2, and be used in a few hundred
  64  *  clock cycles, after which it stays in cache until evicted (normal caching).
  65  *
  66  * \param m Pointer to location prefetch. There are no alignment requirements,
  67  *        but if the pointer is not aligned the prefetch might start at the
  68  *        lower cache line boundary (meaning fewer bytes are prefetched).
  69  */
  70 static inline void gmx_unused
  71 simdPrefetch(void gmx_unused * m)
  72 {
  73     // Do nothing for reference implementation
  74 }
  75
  76 }      // namespace gmx
  77
  78 #endif // GMX_SIMD_IMPL_REFERENCE_GENERAL_H