Update MIS-2 and aggregation

Bringing in newest versions from work on the IPDPS paper.

example/wiki/graph/KokkosGraph_wiki_coarsening.cpp

@@ -1,28 +1,28 @@
 #include "KokkosGraph_wiki_9pt_stencil.hpp"
 #include "KokkosGraph_MIS2.hpp"
 
-int main()
-{
+int main() {
   Kokkos::initialize();
   {
     using GraphDemo::numVertices;
     RowmapType rowmapDevice;
     ColindsType colindsDevice;
-    //Step 1: Generate the graph on host, allocate space on device, and copy.
-    //See function "generate9pt" below.
+    // Step 1: Generate the graph on host, allocate space on device, and copy.
+    // See function "generate9pt" below.
     GraphDemo::generate9pt(rowmapDevice, colindsDevice);
-    //Step 2: Run MIS-2 based coarsening and print the result
+    // Step 2: Run MIS-2 based coarsening and print the result
     {
       std::cout << "Coarsened vertex labels:\n";
       Ordinal numClusters = 0;
-      auto labels = KokkosGraph::Experimental::graph_mis2_coarsen<ExecSpace, RowmapType, ColindsType>(
-          rowmapDevice, colindsDevice, numClusters, KokkosGraph::MIS2_FAST);
-      //coarsening labels can be printed in the same way as colors
+      auto labels =
+          KokkosGraph::Experimental::graph_mis2_aggregate<ExecSpace, RowmapType,
+                                                          ColindsType>(
+              rowmapDevice, colindsDevice, numClusters);
+      // coarsening labels can be printed in the same way as colors
       GraphDemo::printColoring(labels, numClusters);
       putchar('\n');
     }
   }
   Kokkos::finalize();
   return 0;
 }
-

src/common/KokkosKernels_SimpleUtils.hpp

@@ -374,6 +374,41 @@ void kk_view_reduce_max(
       ReduceMaxFunctor<view_type>(view_to_reduce), max_reduction);
 }
 
+// xorshift hash/pseudorandom function (supported for 32- and 64-bit integer
+// types only)
+template <typename Value>
+KOKKOS_FORCEINLINE_FUNCTION Value xorshiftHash(Value v) {
+  static_assert(std::is_unsigned<Value>::value,
+                "xorshiftHash: value must be an unsigned integer type");
+  uint64_t x = v;
+  x ^= x >> 12;
+  x ^= x << 25;
+  x ^= x >> 27;
+  if (std::is_same<Value, uint32_t>::value) {
+    return static_cast<Value>((x * 2685821657736338717ULL - 1) >> 16);
+  }
+  return static_cast<Value>(x * 2685821657736338717ULL - 1);
+}
+
+template <typename V>
+struct SequentialFillFunctor {
+  using size_type = typename V::size_type;
+  using val_type  = typename V::non_const_value_type;
+  SequentialFillFunctor(const V &v_, val_type start_) : v(v_), start(start_) {}
+  KOKKOS_INLINE_FUNCTION void operator()(size_type i) const {
+    v(i) = start + (val_type)i;
+  }
+  V v;
+  val_type start;
+};
+
+template <typename V>
+void sequential_fill(const V &v, typename V::non_const_value_type start = 0) {
+  Kokkos::parallel_for(
+      Kokkos::RangePolicy<typename V::execution_space>(0, v.extent(0)),
+      SequentialFillFunctor<V>(v, start));
+}
+
 }  // namespace Impl
 }  // namespace KokkosKernels
 

src/graph/KokkosGraph_MIS2.hpp

@@ -85,19 +85,42 @@ template <typename device_t, typename rowmap_t, typename colinds_t,
           typename labels_t = typename colinds_t::non_const_type>
 labels_t graph_mis2_coarsen(
     const rowmap_t& rowmap, const colinds_t& colinds,
-    typename colinds_t::non_const_value_type& numClusters,
-    MIS2_Algorithm algo = MIS2_FAST) {
+    typename colinds_t::non_const_value_type& numClusters) {
   if (rowmap.extent(0) <= 1) {
     // there are no vertices to label
     numClusters = 0;
     return labels_t();
   }
-  labels_t mis2 = graph_d2_mis<device_t, rowmap_t, colinds_t, labels_t>(
-      rowmap, colinds, algo);
-  numClusters = mis2.extent(0);
-  Impl::D2_MIS_Coarsening<device_t, rowmap_t, colinds_t, labels_t> coarsening(
-      rowmap, colinds, mis2);
-  return coarsening.compute();
+  Impl::D2_MIS_Aggregation<device_t, rowmap_t, colinds_t, labels_t> aggregation(
+      rowmap, colinds);
+  aggregation.compute(false);
+  numClusters = aggregation.numAggs;
+  return aggregation.labels;
+}
+
+template <typename device_t, typename rowmap_t, typename colinds_t,
+          typename labels_t = typename colinds_t::non_const_type>
+labels_t graph_mis2_aggregate(
+    const rowmap_t& rowmap, const colinds_t& colinds,
+    typename colinds_t::non_const_value_type& numAggregates) {
+  if (rowmap.extent(0) <= 1) {
+    // there are no vertices to label
+    numAggregates = 0;
+    return labels_t();
+  }
+  Impl::D2_MIS_Aggregation<device_t, rowmap_t, colinds_t, labels_t> aggregation(
+      rowmap, colinds);
+  aggregation.compute(true);
+  numAggregates = aggregation.numAggs;
+  return aggregation.labels;
+}
+
+inline const char* mis2_algorithm_name(MIS2_Algorithm algo) {
+  switch (algo) {
+    case MIS2_QUALITY: return "MIS2_QUALITY";
+    case MIS2_FAST: return "MIS2_FAST";
+  }
+  return "*** Invalid MIS2 algo enum value.\n";
 }
 
 }  // end namespace Experimental