[Feature] aten::Relabel_() for the GPU (#3445)

* relabel gpu

* unittest for ralebl_ on the GPU

* finish Relabel_ for the GPU

* copyright

* re-enable the unittest for edge_subgrah on the GPU

* fix unittest for tensorflow

* use a fixed number of threads
Co-authored-by: Jinjing Zhou <VoVAllen@users.noreply.github.com>
Co-authored-by: nv-dlasalle <63612878+nv-dlasalle@users.noreply.github.com>
Co-authored-by: Quan (Andy) Gan <coin2028@hotmail.com>

src/array/array.cc

 /*!
- *  Copyright (c) 2019 by Contributors
+ *  Copyright (c) 2019-2021 by Contributors
  * \file array/array.cc
  * \brief DGL array utilities implementation
  */
@@ -205,7 +205,7 @@ NDArray Repeat(NDArray array, IdArray repeats) {
 
 IdArray Relabel_(const std::vector<IdArray>& arrays) {
   IdArray ret;
-  ATEN_XPU_SWITCH(arrays[0]->ctx.device_type, XPU, "Relabel_", {
+  ATEN_XPU_SWITCH_CUDA(arrays[0]->ctx.device_type, XPU, "Relabel_", {
     ATEN_ID_TYPE_SWITCH(arrays[0]->dtype, IdType, {
       ret = impl::Relabel_<XPU, IdType>(arrays);
     });

src/array/cuda/array_op_impl.cu

 /*!
- *  Copyright (c) 2020 by Contributors
+ *  Copyright (c) 2020-2021 by Contributors
  * \file array/cuda/array_op_impl.cu
  * \brief Array operator GPU implementation
  */
 #include <dgl/array.h>
 #include "../../runtime/cuda/cuda_common.h"
+#include "../../runtime/cuda/cuda_hashtable.cuh"
 #include "./utils.h"
 #include "../arith.h"
 
 namespace dgl {
 using runtime::NDArray;
+using namespace runtime::cuda;
 namespace aten {
 namespace impl {
 
@@ -258,6 +260,84 @@ IdArray Range(IdType low, IdType high, DLContext ctx) {
 template IdArray Range<kDLGPU, int32_t>(int32_t, int32_t, DLContext);
 template IdArray Range<kDLGPU, int64_t>(int64_t, int64_t, DLContext);
 
+///////////////////////////// Relabel_ //////////////////////////////
+
+template <typename IdType>
+__global__ void _RelabelKernel(
+    IdType* out, int64_t length, DeviceOrderedHashTable<IdType> table) {
+
+  int tx = blockIdx.x * blockDim.x + threadIdx.x;
+  int stride_x = gridDim.x * blockDim.x;
+
+  while (tx < length) {
+    out[tx] = table.Search(out[tx])->local;
+    tx += stride_x;
+  }
+}
+
+template <DLDeviceType XPU, typename IdType>
+IdArray Relabel_(const std::vector<IdArray>& arrays) {
+  IdArray all_nodes = Concat(arrays);
+  const int64_t total_length = all_nodes->shape[0];
+
+  if (total_length == 0) {
+    return all_nodes;
+  }
+
+  const auto& ctx = arrays[0]->ctx;
+  auto device = runtime::DeviceAPI::Get(ctx);
+  auto* thr_entry = runtime::CUDAThreadEntry::ThreadLocal();
+
+  // build node maps and get the induced nodes
+  OrderedHashTable<IdType> node_map(total_length, ctx, thr_entry->stream);
+  int64_t num_induced = 0;
+  int64_t * num_induced_device = static_cast<int64_t*>(
+      device->AllocWorkspace(ctx, sizeof(int64_t)));
+  IdArray induced_nodes = NewIdArray(total_length, ctx, sizeof(IdType)*8);
+
+  CUDA_CALL(cudaMemsetAsync(
+    num_induced_device,
+    0,
+    sizeof(*num_induced_device),
+    thr_entry->stream));
+
+  node_map.FillWithDuplicates(
+    all_nodes.Ptr<IdType>(),
+    all_nodes->shape[0],
+    induced_nodes.Ptr<IdType>(),
+    num_induced_device,
+    thr_entry->stream);
+
+  device->CopyDataFromTo(
+    num_induced_device, 0,
+    &num_induced, 0,
+    sizeof(num_induced),
+    ctx,
+    DGLContext{kDLCPU, 0},
+    DGLType{kDLInt, 64, 1},
+    thr_entry->stream);
+  device->StreamSync(ctx, thr_entry->stream);
+  device->FreeWorkspace(ctx, num_induced_device);
+
+  // resize the induced nodes
+  induced_nodes->shape[0] = num_induced;
+
+  // relabel
+  const int nt = 128;
+  for (IdArray arr : arrays) {
+    const int64_t length = arr->shape[0];
+    int nb = (length + nt - 1) / nt;
+    CUDA_KERNEL_CALL((_RelabelKernel<IdType>),
+      nb, nt, 0, thr_entry->stream,
+      arr.Ptr<IdType>(), length, node_map.DeviceHandle());
+  }
+
+  return induced_nodes;
+}
+
+template IdArray Relabel_<kDLGPU, int32_t>(const std::vector<IdArray>& arrays);
+template IdArray Relabel_<kDLGPU, int64_t>(const std::vector<IdArray>& arrays);
+
 ///////////////////////////// AsNumBits /////////////////////////////
 
 template <typename InType, typename OutType>

src/graph/heterograph.cc

@@ -48,8 +48,6 @@ HeteroSubgraph EdgeSubgraphNoPreserveNodes(
     const HeteroGraph* hg, const std::vector<IdArray>& eids) {
   // TODO(minjie): In general, all relabeling should be separated with subgraph
   //   operations.
-  CHECK(hg->Context().device_type != kDLGPU)
-    << "Edge subgraph with relabeling does not support GPU.";
   CHECK_EQ(eids.size(), hg->NumEdgeTypes())
     << "Invalid input: the input list size must be the same as the number of edge type.";
   HeteroSubgraph ret;

tests/compute/test_subgraph.py

@@ -28,7 +28,6 @@ def generate_graph(grad=False, add_data=True):
         g.edata['l'] = ecol
     return g
 
-@unittest.skipIf(F._default_context_str == 'gpu', reason="GPU not implemented")
 def test_edge_subgraph():
     # Test when the graph has no node data and edge data.
     g = generate_graph(add_data=False)
@@ -140,8 +139,6 @@ def test_subgraph_mask(idtype):
     sg1 = g.subgraph({'user': F.tensor([False, True, True], dtype=F.bool),
                       'game': F.tensor([True, False, False, False], dtype=F.bool)})
     _check_subgraph(g, sg1)
-    if F._default_context_str != 'gpu':
-        # TODO(minjie): enable this later
     sg2 = g.edge_subgraph({'follows': F.tensor([False, True], dtype=F.bool),
                            'plays': F.tensor([False, True, False, False], dtype=F.bool),
                            'wishes': F.tensor([False, True], dtype=F.bool)})
@@ -181,8 +178,6 @@ def test_subgraph1(idtype):
 
     sg1 = g.subgraph({'user': [1, 2], 'game': [0]})
     _check_subgraph(g, sg1)
-    if F._default_context_str != 'gpu':
-        # TODO(minjie): enable this later
     sg2 = g.edge_subgraph({'follows': [1], 'plays': [1], 'wishes': [1]})
     _check_subgraph(g, sg2)
 
@@ -190,8 +185,6 @@ def test_subgraph1(idtype):
     sg1 = g.subgraph({'user': F.tensor([1, 2], dtype=idtype),
                       'game': F.tensor([0], dtype=idtype)})
     _check_subgraph(g, sg1)
-    if F._default_context_str != 'gpu':
-        # TODO(minjie): enable this later
     sg2 = g.edge_subgraph({'follows': F.tensor([1], dtype=idtype),
                            'plays': F.tensor([1], dtype=idtype),
                            'wishes': F.tensor([1], dtype=idtype)})
@@ -201,8 +194,6 @@ def test_subgraph1(idtype):
     sg1 = g.subgraph({'user': np.array([1, 2]),
                       'game': np.array([0])})
     _check_subgraph(g, sg1)
-    if F._default_context_str != 'gpu':
-        # TODO(minjie): enable this later
     sg2 = g.edge_subgraph({'follows': np.array([1]),
                            'plays': np.array([1]),
                            'wishes': np.array([1])})
@@ -248,8 +239,6 @@ def test_subgraph1(idtype):
 
     sg1_graph = g_graph.subgraph([1, 2])
     _check_subgraph_single_ntype(g_graph, sg1_graph)
-    if F._default_context_str != 'gpu':
-        # TODO(minjie): enable this later
     sg1_graph = g_graph.edge_subgraph([1])
     _check_subgraph_single_ntype(g_graph, sg1_graph)
     sg1_graph = g_graph.edge_subgraph([1], relabel_nodes=False)
@@ -297,8 +286,6 @@ def test_subgraph1(idtype):
     _check_typed_subgraph1(g, sg5)
 
     # Test for restricted format
-    if F._default_context_str != 'gpu':
-        # TODO(minjie): enable this later
     for fmt in ['csr', 'csc', 'coo']:
         g = dgl.graph(([0, 1], [1, 2])).formats(fmt)
         sg = g.subgraph({g.ntypes[0]: [1, 0]})
@@ -309,8 +296,6 @@ def test_subgraph1(idtype):
         dst = F.asnumpy(dst)
         assert np.array_equal(src, np.array([1]))
 
-
-@unittest.skipIf(F._default_context_str == 'gpu', reason="GPU not implemented")
 @parametrize_dtype
 def test_in_subgraph(idtype):
     hg = dgl.heterograph({
@@ -318,7 +303,7 @@ def test_in_subgraph(idtype):
         ('user', 'play', 'game'): ([0, 0, 1, 3], [0, 1, 2, 2]),
         ('game', 'liked-by', 'user'): ([2, 2, 2, 1, 1, 0], [0, 1, 2, 0, 3, 0]),
         ('user', 'flips', 'coin'): ([0, 1, 2, 3], [0, 0, 0, 0])
-    }, idtype=idtype, num_nodes_dict={'user': 5, 'game': 10, 'coin': 8})
+    }, idtype=idtype, num_nodes_dict={'user': 5, 'game': 10, 'coin': 8}).to(F.ctx())
     subg = dgl.in_subgraph(hg, {'user' : [0,1], 'game' : 0})
     assert subg.idtype == idtype
     assert len(subg.ntypes) == 3
@@ -378,7 +363,6 @@ def test_in_subgraph(idtype):
     assert subg.num_nodes('coin') == 0
     assert subg.num_edges('flips') == 0
 
-@unittest.skipIf(F._default_context_str == 'gpu', reason="GPU not implemented")
 @parametrize_dtype
 def test_out_subgraph(idtype):
     hg = dgl.heterograph({
@@ -386,7 +370,7 @@ def test_out_subgraph(idtype):
         ('user', 'play', 'game'): ([0, 0, 1, 3], [0, 1, 2, 2]),
         ('game', 'liked-by', 'user'): ([2, 2, 2, 1, 1, 0], [0, 1, 2, 0, 3, 0]),
         ('user', 'flips', 'coin'): ([0, 1, 2, 3], [0, 0, 0, 0])
-    }, idtype=idtype)
+    }, idtype=idtype).to(F.ctx())
     subg = dgl.out_subgraph(hg, {'user' : [0,1], 'game' : 0})
     assert subg.idtype == idtype
     assert len(subg.ntypes) == 3

tests/cpp/test_aten.cc

@@ -242,14 +242,14 @@ TEST(ArrayTest, TestIndexSelect) {
 }
 
 template <typename IDX>
-void _TestRelabel_() {
-  IdArray a = aten::VecToIdArray(std::vector<IDX>({0, 20, 10}), sizeof(IDX)*8, CTX);
-  IdArray b = aten::VecToIdArray(std::vector<IDX>({20, 5, 6}), sizeof(IDX)*8, CTX);
+void _TestRelabel_(DLContext ctx) {
+  IdArray a = aten::VecToIdArray(std::vector<IDX>({0, 20, 10}), sizeof(IDX)*8, ctx);
+  IdArray b = aten::VecToIdArray(std::vector<IDX>({20, 5, 6}), sizeof(IDX)*8, ctx);
   IdArray c = aten::Relabel_({a, b});
 
-  IdArray ta = aten::VecToIdArray(std::vector<IDX>({0, 1, 2}), sizeof(IDX)*8, CTX);
-  IdArray tb = aten::VecToIdArray(std::vector<IDX>({1, 3, 4}), sizeof(IDX)*8, CTX);
-  IdArray tc = aten::VecToIdArray(std::vector<IDX>({0, 20, 10, 5, 6}), sizeof(IDX)*8, CTX);
+  IdArray ta = aten::VecToIdArray(std::vector<IDX>({0, 1, 2}), sizeof(IDX)*8, ctx);
+  IdArray tb = aten::VecToIdArray(std::vector<IDX>({1, 3, 4}), sizeof(IDX)*8, ctx);
+  IdArray tc = aten::VecToIdArray(std::vector<IDX>({0, 20, 10, 5, 6}), sizeof(IDX)*8, ctx);
 
   ASSERT_TRUE(ArrayEQ<IDX>(a, ta));
   ASSERT_TRUE(ArrayEQ<IDX>(b, tb));
@@ -257,8 +257,12 @@ void _TestRelabel_() {
 }
 
 TEST(ArrayTest, TestRelabel_) {
-  _TestRelabel_<int32_t>();
-  _TestRelabel_<int64_t>();
+  _TestRelabel_<int32_t>(CPU);
+  _TestRelabel_<int64_t>(CPU);
+#ifdef DGL_USE_CUDA
+  _TestRelabel_<int32_t>(GPU);
+  _TestRelabel_<int64_t>(GPU);
+#endif
 }
 
 template <typename IDX>