[GitHub] HyperZealot commented on a change in pull request #14090: Add GPU version of contrib.boolean_mask

[GitBox <gi...@apache.org>]

HyperZealot commented on a change in pull request #14090: Add GPU version of contrib.boolean_mask
URL: https://github.com/apache/incubator-mxnet/pull/14090#discussion_r255280324
 
 

 ##########
 File path: src/operator/contrib/boolean_mask.cu
 ##########
 @@ -0,0 +1,191 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+/*!
+ * Copyright (c) 2018 by Contributors
+ * \file boolean_mask.cu
+*/
+
+#include "./boolean_mask-inl.h"
+#include <cub/cub.cuh>
+
+namespace mxnet {
+namespace op {
+
+struct BooleanMaskForwardKernel {
+  template<typename DType>
+  static void MSHADOW_XINLINE Map(int i,
+                                  DType* out,
+                                  const DType* data,
+                                  const int32_t* idx,
+                                  const size_t col_size) {
+    int row_id = i / col_size;
+    int col_id = i % col_size;
+    int32_t prev = (row_id == 0) ? 0 : idx[row_id - 1];
+    int32_t curr = idx[row_id];
+    if (prev != curr) {
+      out[prev * col_size + col_id] = data[i];
+    }
+  }
+};
+
+struct BooleanMaskBackwardKernel {
+  template<typename DType>
+  static void MSHADOW_XINLINE Map(int i,
+                                  DType* igrad,
+                                  const DType* ograd,
+                                  const int32_t* idx,
+                                  const size_t col_size) {
+    int row_id = i / col_size;
+    int col_id = i % col_size;
+    int32_t prev = (row_id == 0) ? 0 : idx[row_id - 1];
+    int32_t curr = idx[row_id];
+    if (prev != curr) {
+      igrad[i] = ograd[prev * col_size + col_id];
+    }
+  }
+};
+
+template<>
+inline void BooleanMaskForward<gpu>(const nnvm::NodeAttrs& attrs,
+                                    const OpContext &ctx,
+                                    const std::vector<NDArray> &inputs,
+                                    const std::vector<OpReqType> &req,
+                                    const std::vector<NDArray> &outputs) {
+  using namespace mshadow;
+  CHECK_EQ(inputs.size(), 2U);
+  CHECK_EQ(outputs.size(), 1U);
+  const BooleanMaskParam& param = nnvm::get<BooleanMaskParam>(attrs.parsed);
+  const int axis = param.axis;
+  const NDArray &data = inputs[0];
+  const NDArray &idx = inputs[1];
+  const NDArray &out = outputs[0];
+  CHECK_EQ(axis, 0) << "Not supported yet";
+  CHECK_EQ(data.shape()[axis], idx.shape()[0]);
+  CHECK_EQ(idx.shape().ndim(), 1U);
+  Stream<gpu>* s = ctx.get_stream<gpu>();
+  // count the number of 1s in `idx`, so that we could know the output dimension
+  size_t idx_size = idx.shape()[0];
+  int32_t valid_num = 0;
+  int32_t* prefix_sum = nullptr;
+  void* d_temp_storage = nullptr;
+  size_t temp_storage_bytes = 0;
+  cub::DeviceScan::InclusiveSum(d_temp_storage,
+                                temp_storage_bytes,
+                                prefix_sum,
+                                prefix_sum,
+                                idx_size,
+                                Stream<gpu>::GetStream(s));
 
 Review comment:
   Done, please check.

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