Update Kokkos library in LAMMPS to v4.5.0

lib/kokkos/example/relocatable_function/main.cpp

@@ -0,0 +1,50 @@
+//@HEADER
+// ************************************************************************
+//
+//                        Kokkos v. 4.0
+//       Copyright (2022) National Technology & Engineering
+//               Solutions of Sandia, LLC (NTESS).
+//
+// Under the terms of Contract DE-NA0003525 with NTESS,
+// the U.S. Government retains certain rights in this software.
+//
+// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
+// See https://kokkos.org/LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//@HEADER
+
+#include <Kokkos_Core.hpp>
+
+#include <iostream>
+
+KOKKOS_RELOCATABLE_FUNCTION void count_even(const long i, long& lcount);
+
+int main(int argc, char* argv[]) {
+  Kokkos::ScopeGuard scope_guard(argc, argv);
+
+  for (int n = 10; n <= 100'000'000; n *= 10) {
+    Kokkos::Timer timer;
+
+    long count = 0;
+    // Compute the number of even integers from 0 to n-1 using a relocatable
+    // functor
+    Kokkos::parallel_reduce(
+        n, KOKKOS_LAMBDA(const long i, long& lcount) { count_even(i, lcount); },
+        count);
+
+    double count_time_relocatable = timer.seconds();
+
+    timer.reset();
+
+    // Compute the number of even integers from 0 to n-1 using an inline lambda
+    Kokkos::parallel_reduce(
+        n,
+        KOKKOS_LAMBDA(const long i, long& lcount) { lcount += (i % 2) == 0; },
+        count);
+
+    double count_time_inline = timer.seconds();
+    std::cout << std::scientific << n * 1. << ' ' << count_time_relocatable
+              << "s (relocatable) vs. " << count_time_inline << "s (inline)\n";
+  }
+}