fix bug of top_k npu op (#36175)

Author: pangyoki

paddle/fluid/operators/top_k_op_npu.cc

@@ -51,7 +51,9 @@ class TopkNPUKernel : public framework::OpKernel<T> {
     indices->mutable_data<int64_t>(ctx.GetPlace());
 
     // prepare assit
-    auto dim = input->dims().size();
+    auto size = input->dims().size();
+    // dim is the last dimension of input
+    auto dim = input->dims()[size - 1];
     framework::Tensor assist_seq_tensor;
     assist_seq_tensor.Resize({2 * dim});
     assist_seq_tensor.mutable_data<T>(ctx.GetPlace());

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

@@ -22,6 +22,7 @@
 import paddle
 import paddle.fluid as fluid
 from paddle.fluid import core
+from test_top_k_v2_op_npu import numpy_topk
 
 paddle.enable_static()
 SEED = 2021
@@ -87,5 +88,40 @@ def test_check_output(self):
         self.check_output_with_place(self.place)
 
 
+class TestTopkV3(OpTest):
+    def setUp(self):
+        self.set_npu()
+        self.place = paddle.NPUPlace(0)
+        self.op_type = "top_k"
+
+        self.init_dtype()
+        self.set_input_data()
+        self.set_attrs()
+        output, indices = numpy_topk(
+            self.input_data, axis=self.axis, k=self.k, largest=True)
+
+        self.inputs = {'X': self.input_data}
+        self.attrs = {'k': self.k, 'axis': self.axis}
+        self.outputs = {'Out': output, 'Indices': indices}
+
+    def set_npu(self):
+        self.__class__.use_npu = True
+        self.__class__.no_need_check_grad = True
+
+    def init_dtype(self):
+        self.dtype = np.float16
+
+    def test_check_output(self):
+        self.check_output_with_place(self.place)
+
+    def set_attrs(self):
+        self.k = 3
+        self.axis = 1
+
+    def set_input_data(self):
+        self.input_data = np.random.choice(
+            10000, size=(10, 20), replace=False).astype(self.dtype)
+
+
 if __name__ == '__main__':
     unittest.main()