prefetch.h

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/*
* (C) 2023 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#ifndef BOTAN_PREFETCH_UTILS_H_
#define BOTAN_PREFETCH_UTILS_H_
 
#include <botan/types.h>
#include <concepts>
#include <type_traits>
 
namespace Botan {
 
/**
* Prefetch an array
*
* This function returns a uint64_t which is accumulated from values
* read from the array. This may help confuse the compiler sufficiently
* to not elide otherwise "useless" reads. The return value will always
* be zero.
*/
uint64_t prefetch_array_raw(size_t bytes, const void* array) noexcept;
 
/**
* Prefetch several arrays
*
* This function returns a uint64_t which is accumulated from values
* read from the array. This may help confuse the compiler sufficiently
* to not elide otherwise "useless" reads. The return value will always
* be zero.
*/
template <std::unsigned_integral T, size_t... Ns>
T prefetch_arrays(T (&... arr)[Ns]) noexcept {
   return (static_cast<T>(prefetch_array_raw(sizeof(T) * Ns, arr)) & ...);
}
 
}  // namespace Botan
 
#endif