chore: import upstream snapshot with attribution

paddle/phi/kernels/cpu/linspace_kernel.cc

@@ -0,0 +1,84 @@
+// Copyright (c) 2022 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 "paddle/phi/kernels/linspace_kernel.h"
+
+#include "paddle/phi/backends/cpu/cpu_context.h"
+#include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/funcs/data_type_transform.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void LinspaceKernel(const Context& dev_ctx,
+                    const DenseTensor& start,
+                    const DenseTensor& stop,
+                    const DenseTensor& number,
+                    DataType dtype,
+                    DenseTensor* out) {
+  int64_t num = 0;
+  if (number.dtype() == DataType::INT64) {
+    num = number.data<int64_t>()[0];
+  } else if (number.dtype() == DataType::INT32) {
+    num = number.data<int32_t>()[0];
+  }
+  PADDLE_ENFORCE_GE(num,
+                    0,
+                    common::errors::InvalidArgument(
+                        "The num of linspace op should be larger "
+                        "than or equal to 0, but received num is %d",
+                        num));
+  if (num == 0) {
+    out->Resize({0});
+    dev_ctx.template Alloc<T>(out);
+    return;
+  }
+  using StepT = std::conditional_t<std::is_integral_v<T>, double, T>;
+  auto start_t = funcs::TransDataType(dev_ctx, start, dtype);
+  auto stop_t = funcs::TransDataType(dev_ctx, stop, dtype);
+
+  T start_data = start_t.template data<T>()[0];
+  T stop_data = stop_t.template data<T>()[0];
+
+  out->Resize({num});
+  T* out_data = dev_ctx.template Alloc<T>(out);
+
+  if (num > 1) {
+    // step should be of StepT type
+    StepT step =
+        (static_cast<StepT>(stop_data) - static_cast<StepT>(start_data)) /
+        (num - 1);
+    int half_num = num / 2;
+    for (int i = 0; i < num; ++i) {
+      if (i < half_num) {
+        out_data[i] = static_cast<T>(start_data + step * i);
+      } else {
+        out_data[i] = static_cast<T>(stop_data - step * (num - i - 1));
+      }
+    }
+  } else {
+    out_data[0] = static_cast<T>(start_data);
+  }
+}
+
+}  // namespace phi
+
+PD_REGISTER_KERNEL(linspace,
+                   CPU,
+                   ALL_LAYOUT,
+                   phi::LinspaceKernel,
+                   float,
+                   int32_t,
+                   int64_t,
+                   double) {}