open_mp.hpp

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// Copyright 2020 Lawrence Livermore National Security, LLC and other Metall
// Project Developers. See the top-level COPYRIGHT file for details.
//
// SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
#ifndef METALL_UTILITY_OPEN_MP_HPP
#define METALL_UTILITY_OPEN_MP_HPP
 
#include <cstdint>
#include <string>
 
#ifdef _OPENMP
#include <omp.h>
#endif
 
#ifdef OPEN_MP_PRAGMA_OPERATOR
#error "OPEN_MP_PRAGMA_OPERATOR is already defined"
#endif
 
#ifdef OMP_DIRECTIVE
#error "OMP_DIRECTIVE is already defined"
#endif
 
#define OPEN_MP_PRAGMA_OPERATOR(x) _Pragma(#x)
#ifdef _OPENMP
#define OMP_DIRECTIVE(directive) OPEN_MP_PRAGMA_OPERATOR(omp directive)
#else
#define OMP_DIRECTIVE(directive)
#endif
 
namespace metall::utility {
 
namespace omp {
 
using omp_sched_type =
#ifdef _OPENMP
    omp_sched_t;
#else
    int;
#endif
 
inline std::string schedule_kind_name(
    [[maybe_unused]] const omp_sched_type kind) {
  std::string name;
 
#ifdef _OPENMP
#if _OPENMP >= 201811  // OpenMP 5.0
  if (kind == omp_sched_static ||
      kind == (omp_sched_static | omp_sched_monotonic)) {
    name = "omp_sched_static";
  } else if (kind == omp_sched_dynamic ||
             kind == (omp_sched_dynamic | omp_sched_monotonic)) {
    name = "omp_sched_dynamic";
  } else if (kind == omp_sched_guided ||
             kind == (omp_sched_guided | omp_sched_monotonic)) {
    name = "omp_sched_guided";
  } else if (kind == omp_sched_auto ||
             kind == (omp_sched_auto | omp_sched_monotonic)) {
    name = "omp_sched_auto";
  } else {
    name = "Unknown kind (" + std::to_string((uint64_t)kind) + ")";
  }
  if (kind & omp_sched_monotonic) {
    name += " with omp_sched_monotonic";
  }
#else
  if (kind == omp_sched_static) {
    name = "omp_sched_static";
  } else if (kind == omp_sched_dynamic) {
    name = "omp_sched_dynamic";
  } else if (kind == omp_sched_guided) {
    name = "omp_sched_guided";
  } else if (kind == omp_sched_auto) {
    name = "omp_sched_auto";
  } else {
    name = "Unknown kind (" + std::to_string((uint64_t)kind) + ")";
  }
#endif
#else
  name = "OpenMP is not supported";
#endif
 
  return name;
}
 
inline std::pair<omp_sched_type, int> get_schedule() {
#ifdef _OPENMP
  omp_sched_t kind;
  int chunk_size;
  ::omp_get_schedule(&kind, &chunk_size);
 
  return std::make_pair(kind, chunk_size);
#else
  return std::make_pair(0, 0);
#endif
}
 
inline int get_num_threads() noexcept {
#ifdef _OPENMP
  return ::omp_get_num_threads();
#else
  return 1;
#endif
}
 
inline int get_thread_num() noexcept {
#ifdef _OPENMP
  return ::omp_get_thread_num();
#else
  return 0;
#endif
}
 
inline void set_num_threads([[maybe_unused]] const int n) noexcept {
#ifdef _OPENMP
  ::omp_set_num_threads(n);
#endif
}
 
}  // namespace omp
}  // namespace metall::utility
 
#endif  // METALL_UTILITY_OPEN_MP_HPP