From 3328eb033e9a66dcc5904f31df5f9f8f0e321a01 Mon Sep 17 00:00:00 2001
From: Chen Weihang <chenweihang@baidu.com>
Date: Wed, 17 Nov 2021 03:32:55 -0600
Subject: [PATCH] [PTen] Add slice api implemention for Tensor (#37276)

* add slice api impl of Tensor

* fix test slice error
---
 paddle/pten/api/lib/tensor.cc           | 16 ++++++--
 paddle/pten/tests/api/CMakeLists.txt    |  1 +
 paddle/pten/tests/api/test_slice_api.cc | 50 +++++++++++++++++++++++++
 3 files changed, 63 insertions(+), 4 deletions(-)
 create mode 100644 paddle/pten/tests/api/test_slice_api.cc

diff --git a/paddle/pten/api/lib/tensor.cc b/paddle/pten/api/lib/tensor.cc
index bb3fba88586..db5fa9f671f 100644
--- a/paddle/pten/api/lib/tensor.cc
+++ b/paddle/pten/api/lib/tensor.cc
@@ -22,6 +22,7 @@ limitations under the License. */
 #include "paddle/pten/api/lib/ext_compat_utils.h"
 #include "paddle/pten/api/lib/utils/allocator.h"
 #include "paddle/pten/api/lib/utils/storage.h"
+#include "paddle/pten/core/compat_utils.h"
 #include "paddle/pten/core/dense_tensor.h"
 #include "paddle/pten/core/tensor_base.h"
 #include "paddle/pten/core/tensor_meta.h"
@@ -236,11 +237,18 @@ template PD_DLL_DECL paddle::platform::complex<double>
 template PD_DLL_DECL paddle::platform::float16 *
 Tensor::data<paddle::platform::float16>();
 
+// TODO(chenweihang): replace slice impl by API
 Tensor Tensor::slice(const int64_t begin_idx, const int64_t end_idx) const {
-  PADDLE_THROW(platform::errors::Unimplemented(
-      "The slice operation is not supported now, "
-      "and it will be implemented by calling the slice kernel later."));
-  return Tensor();
+  if (detail::IsDenseTensor(impl_)) {
+    return Tensor(std::make_shared<pten::DenseTensor>(
+        std::move(pten::CompatibleDenseTensorUtils::Slice(
+            std::dynamic_pointer_cast<pten::DenseTensor>(impl_).get(),
+            begin_idx,
+            end_idx))));
+  } else {
+    PADDLE_THROW(platform::errors::Unimplemented(
+        "Only supported slice operation on DenseTensor now."));
+  }
 }
 
 std::shared_ptr<pten::TensorBase> Tensor::impl() const { return impl_; }
diff --git a/paddle/pten/tests/api/CMakeLists.txt b/paddle/pten/tests/api/CMakeLists.txt
index 5bc5f0ace88..9e688d8200b 100644
--- a/paddle/pten/tests/api/CMakeLists.txt
+++ b/paddle/pten/tests/api/CMakeLists.txt
@@ -15,3 +15,4 @@ cc_test(test_fill_api SRCS test_fill_api.cc DEPS pten_tensor pten_api pten_api_u
 cc_test(test_flatten_api SRCS test_flatten_api.cc DEPS pten_tensor pten_api pten_api_utils)
 cc_test(test_elementwise_api SRCS test_elementwise_api.cc DEPS pten_tensor pten_api pten_api_utils)
 cc_test(test_reshape_api SRCS test_reshape_api.cc DEPS pten_tensor pten_api pten_api_utils)
+cc_test(test_slice_api SRCS test_slice_api.cc DEPS pten_tensor pten_api pten_api_utils)
diff --git a/paddle/pten/tests/api/test_slice_api.cc b/paddle/pten/tests/api/test_slice_api.cc
new file mode 100644
index 00000000000..eb8be21bcbb
--- /dev/null
+++ b/paddle/pten/tests/api/test_slice_api.cc
@@ -0,0 +1,50 @@
+/* Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
+
+Licensed 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. */
+
+#include <gtest/gtest.h>
+#include <memory>
+
+#include "paddle/pten/api/include/creation.h"
+#include "paddle/pten/api/include/tensor.h"
+#include "paddle/pten/core/kernel_registry.h"
+
+PT_DECLARE_MODULE(CreationCPU);
+
+#if defined(PADDLE_WITH_CUDA) || defined(PADDLE_WITH_HIP)
+PT_DECLARE_MODULE(CreationCUDA);
+#endif
+
+namespace pten {
+namespace tests {
+
+TEST(Tensor, slice) {
+  auto x = paddle::experimental::full({4, 3}, 1, pten::DataType::INT64);
+  auto slice_x = x.slice(1, 2);
+
+  // check slice result
+  ASSERT_EQ(slice_x.dims().size(), 2);
+  ASSERT_EQ(slice_x.dims()[0], 1);
+  ASSERT_EQ(slice_x.dims()[1], 3);
+  ASSERT_EQ(slice_x.numel(), 3);
+  ASSERT_EQ(slice_x.is_cpu(), true);
+  ASSERT_EQ(slice_x.type(), pten::DataType::INT64);
+  ASSERT_EQ(slice_x.layout(), pten::DataLayout::NCHW);
+  ASSERT_EQ(slice_x.initialized(), true);
+  for (int64_t i = 0; i < slice_x.numel(); ++i) {
+    ASSERT_EQ(slice_x.mutable_data<int64_t>()[i], 1);
+  }
+}
+
+}  // namespace tests
+}  // namespace pten
-- 
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