flash-attention/csrc/cutlass/include/cute/algorithm/fill.hpp

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#pragma once

#include <cute/config.hpp>

#include <cute/tensor.hpp>
#include <cute/algorithm/prefer.hpp>

namespace cute
{

//
// Accept mutable temporaries
//
template <class Engine, class Layout, class T>
CUTE_HOST_DEVICE
void
fill(Tensor<Engine, Layout>&& tensor, T const& value)
{
  return fill(tensor, value);
}

namespace detail
{

// Prefer fill(tensor.data(), value), if possible
template <class Engine, class Layout, class T>
CUTE_HOST_DEVICE
auto
fill(Tensor<Engine, Layout>& tensor, T const& value, prefer<1>)
    -> decltype(fill(tensor.data(), value))
{
  fill(tensor.data(), value);
}

// Default implementation
template <class Engine, class Layout, class T>
CUTE_HOST_DEVICE
void
fill(Tensor<Engine, Layout>& tensor, T const& value, prefer<0>)
{
  CUTE_UNROLL
  for (int i = 0; i < size(tensor); ++i) {
    tensor(i) = value;
  }
}

} // end namespace detail

template <class Engine, class Layout, class T>
CUTE_HOST_DEVICE
void
fill(Tensor<Engine, Layout>& tensor, T const& value)
{
  return detail::fill(tensor, value, prefer<1>{});
}

} // end namespace cute