[NPU] Support npu op flatten2_grad

paddle/fluid/operators/flatten_op_npu.cc

@@ -34,6 +34,26 @@ class Flatten2NPUKernel : public framework::OpKernel<T> {
     runner.Run(stream);
   }
 };
+
+template <typename T>
+class Flatten2GradNPUKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext &ctx) const override {
+    auto *d_x = ctx.Output<framework::LoDTensor>(framework::GradVarName("X"));
+    auto *d_out =
+        ctx.Input<framework::LoDTensor>(framework::GradVarName("Out"));
+
+    auto xshape_dims = ctx.Input<framework::LoDTensor>("XShape")->dims();
+    auto x_dims = framework::slice_ddim(xshape_dims, 1, xshape_dims.size());
+
+    d_x->mutable_data(ctx.GetPlace(), d_out->type());
+    framework::TensorCopy(
+        *d_out, ctx.GetPlace(),
+        ctx.template device_context<paddle::platform::NPUDeviceContext>(), d_x);
+    d_x->Resize(x_dims);
+  }
+};
+
 }  // namespace operators
 }  // namespace paddle
 
@@ -45,3 +65,9 @@ REGISTER_OP_NPU_KERNEL(flatten2, ops::Flatten2NPUKernel<float>,
                        ops::Flatten2NPUKernel<int>,
                        ops::Flatten2NPUKernel<int8_t>,
                        ops::Flatten2NPUKernel<int64_t>);
+REGISTER_OP_NPU_KERNEL(flatten2_grad, ops::Flatten2GradNPUKernel<float>,
+                       ops::Flatten2GradNPUKernel<double>,
+                       ops::Flatten2GradNPUKernel<uint8_t>,
+                       ops::Flatten2GradNPUKernel<int>,
+                       ops::Flatten2GradNPUKernel<int8_t>,
+                       ops::Flatten2GradNPUKernel<int64_t>);

python/paddle/fluid/tests/unittests/npu/test_flatten2_op_npu.py

@@ -43,6 +43,9 @@ def set_npu(self):
     def test_check_output(self):
         self.check_output_with_place(self.place, no_check_set=["XShape"])
 
+    def test_check_grad(self):
+        self.check_grad_with_place(self.place, ["X"], "Out")
+
     def init_test_case(self):
         self.in_shape = (3, 2, 4, 5)
         self.axis = 1