add example6 - find a 2d pattern in a distributed_mdarray (#9)

* add example6 - find a 2d pattern in a distributed_mdarray

* add a new example to the workflow and the script

* small review fixes

removed ifdef, added a comment describing the example

* remove an unnecessary submdspan

Author: haichangsi

.github/workflows/docker_workflow.yml

@@ -52,3 +52,4 @@ jobs:
           mpirun -n 3 ./build/src/example3
           mpirun -n 3 ./build/src/example4
           mpirun -n 3 ./build/src/example5
+          mpirun -n 3 ./build/src/example6

scripts/build_run.sh

@@ -10,8 +10,9 @@ export CC=icx
 cmake -B build
 cmake --build build -j
 
-mpirun -n 2 ./build/src/example1
-mpirun -n 2 ./build/src/example2
-mpirun -n 2 ./build/src/example3
-mpirun -n 2 ./build/src/example4
-mpirun -n 2 ./build/src/example5
+mpirun -n 3 ./build/src/example1
+mpirun -n 3 ./build/src/example2
+mpirun -n 3 ./build/src/example3
+mpirun -n 3 ./build/src/example4
+mpirun -n 3 ./build/src/example5
+mpirun -n 3 ./build/src/example6

src/CMakeLists.txt

@@ -36,3 +36,8 @@ add_executable(example5 example5.cpp)
 
 target_compile_definitions(example5 INTERFACE DR_FORMAT)
 target_link_libraries(example5 DR::mpi fmt::fmt)
+
+add_executable(example6 example6.cpp)
+
+target_compile_definitions(example6 INTERFACE DR_FORMAT)
+target_link_libraries(example6 DR::mpi fmt::fmt)

src/example6.cpp

@@ -0,0 +1,59 @@
+// SPDX-FileCopyrightText: Intel Corporation
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include <dr/mhp.hpp>
+#include <fmt/core.h>
+
+namespace mhp = dr::mhp;
+
+using T = uint16_t;
+using MDA = dr::mhp::distributed_mdarray<T, 2>;
+
+/* 2D pattern search in a distributed multidimensional (2D) array */
+int main() {
+  mhp::init(sycl::default_selector_v);
+
+  std::size_t arr_size = 7;
+  // keep in mind that if you change the pattern size, you have to also change
+  // the pattern array
+  const std::size_t pattern_size = 2;
+  const std::size_t radius = pattern_size - 1;
+  std::array slice_starts{radius - 1, radius - 1};
+  std::array slice_ends{arr_size - radius, arr_size - radius};
+
+  auto dist = dr::mhp::distribution().halo(radius);
+  MDA a({arr_size, arr_size}, dist);
+  MDA occurrences_coords({arr_size, arr_size});
+
+  mhp::iota(a, 1);
+  mhp::transform(a, a.begin(), [](auto &&v) { return v % 2; });
+  mhp::fill(occurrences_coords, 0);
+
+  auto a_submdspan =
+      dr::mhp::views::submdspan(a.view(), slice_starts, slice_ends);
+  int pattern[pattern_size][pattern_size] = {{1, 0}, {0, 1}};
+
+  auto mdspan_pattern_op = [pattern](auto &&v) {
+    auto [a_submdspan, occurrences] = v;
+    if (pattern[0][0] == a_submdspan(0, 0) &&
+        pattern[0][1] == a_submdspan(0, 1) &&
+        pattern[1][0] == a_submdspan(1, 0) &&
+        pattern[1][1] == a_submdspan(1, 1)) {
+      occurrences(0, 0) = 1;
+    }
+  };
+
+  mhp::halo(a).exchange();
+  mhp::stencil_for_each(mdspan_pattern_op, a_submdspan, occurrences_coords);
+
+  if (mhp::rank() == 0) {
+    fmt::print("a: \n{} \n", a.mdspan());
+    fmt::print("pattern: \n{} \n", pattern);
+    fmt::print("occurrences: \n{} \n", occurrences_coords.mdspan());
+  }
+
+  mhp::finalize();
+
+  return 0;
+}