flash-attention/csrc/cutlass/include/cute/container/alignment.hpp

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#pragma once

#include <cute/config.hpp>

#include <cute/numeric/numeric_types.hpp>
#include <cute/numeric/math.hpp>

namespace cute
{

// Test if a pointer is aligned to N bytes
template <int N>
CUTE_HOST_DEVICE constexpr
bool
is_byte_aligned(void const* const ptr)
{
  static_assert(N > 0 && (N & (N - 1)) == 0, "N must be a power of 2 in alignment check");
  return (reinterpret_cast<uintptr_t>(ptr) & (N-1)) == 0;
}

#if defined(__CUDACC__)
#  define CUTE_ALIGNAS(n) __align__(n)
#else
#  define CUTE_ALIGNAS(n) alignas(n)
#endif

template <size_t Alignment>
struct aligned_struct {};

template <> struct CUTE_ALIGNAS(  1) aligned_struct<  1> {};
template <> struct CUTE_ALIGNAS(  2) aligned_struct<  2> {};
template <> struct CUTE_ALIGNAS(  4) aligned_struct<  4> {};
template <> struct CUTE_ALIGNAS(  8) aligned_struct<  8> {};
template <> struct CUTE_ALIGNAS( 16) aligned_struct< 16> {};
template <> struct CUTE_ALIGNAS( 32) aligned_struct< 32> {};
template <> struct CUTE_ALIGNAS( 64) aligned_struct< 64> {};
template <> struct CUTE_ALIGNAS(128) aligned_struct<128> {};
template <> struct CUTE_ALIGNAS(256) aligned_struct<256> {};

} // end namespace cute