chore: import upstream snapshot with attribution

paddle/phi/kernels/cpu/where_grad_kernel.cc

@@ -0,0 +1,68 @@
+// 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/where_grad_kernel.h"
+
+#include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/full_kernel.h"
+namespace phi {
+
+template <typename T, typename Context>
+void WhereGradKernel(const Context& dev_ctx,
+                     const DenseTensor& condition,
+                     const DenseTensor& x UNUSED,
+                     const DenseTensor& y UNUSED,
+                     const DenseTensor& out_grad,
+                     DenseTensor* x_grad,
+                     DenseTensor* y_grad) {
+  const auto* cond_data = condition.data<bool>();
+  auto numel = condition.numel();
+  auto* dout = out_grad.data<T>();
+  if (out_grad.numel() == 0) {
+    if (x_grad) {
+      Full<T, Context>(dev_ctx, x_grad->dims(), static_cast<T>(0), x_grad);
+    }
+    if (y_grad) {
+      Full<T, Context>(dev_ctx, y_grad->dims(), static_cast<T>(0), y_grad);
+    }
+    return;
+  }
+
+  if (x_grad != nullptr) {
+    auto* dx = dev_ctx.template Alloc<T>(x_grad);
+    for (int i = 0; i < numel; i++) {
+      dx[i] = cond_data[i] ? dout[i] : T{};
+    }
+  }
+  if (y_grad != nullptr) {
+    auto* dy = dev_ctx.template Alloc<T>(y_grad);
+    for (int i = 0; i < numel; i++) {
+      dy[i] = cond_data[i] ? T{} : dout[i];
+    }
+  }
+}
+
+}  // namespace phi
+
+PD_REGISTER_KERNEL(where_grad,
+                   CPU,
+                   ALL_LAYOUT,
+                   phi::WhereGradKernel,
+                   float,
+                   double,
+                   int,
+                   int64_t,
+                   bool,
+                   phi::complex64,
+                   phi::complex128) {}