!4718 fix avgpoolgrad

Merge pull request !4718 from fangzehua/avg0819

mindspore/ops/_grad/grad_nn_ops.py

@@ -232,6 +232,8 @@ def _get_mean_matrix(x_shape, ksize, stride, padding, x_dtype):
 
     n_input, c_input, h_input, w_input = x_shape
     h_ksize, w_ksize = ksize[2], ksize[3]
+    if h_ksize == h_input and w_ksize == w_input and padding == "VALID":
+        return None
     h_stride, w_stride = stride[2], stride[3]
     n_output = n_input
     c_output = c_input
@@ -268,7 +270,11 @@ def _get_mean_matrix(x_shape, ksize, stride, padding, x_dtype):
 
 
 @constexpr
-def _get_kernel_matrix(kernel_matrix_shape, x_dtype):
+def _get_kernel_matrix(x_shape_nchw, kernel_matrix_shape, padding, x_dtype):
+    if x_shape_nchw[2] == kernel_matrix_shape[2] \
+        and x_shape_nchw[3] == kernel_matrix_shape[3] \
+        and padding == 'VALID':
+        return None
     kernel_matrix = np.ones(kernel_matrix_shape)
     return Tensor(kernel_matrix, x_dtype)
 
@@ -319,7 +325,7 @@ def get_bprop_avg_pool_grad(self):
                                    k_size_nchw[2],
                                    k_size_nchw[3])
             mean_matrix = _get_mean_matrix(x_shape_nchw, k_size_nchw, stride_nchw, padding, x_dtype)
-            kernel_matrix = _get_kernel_matrix(kernel_matrix_shape, x_dtype)
+            kernel_matrix = _get_kernel_matrix(x_shape_nchw, kernel_matrix_shape, padding, x_dtype)
             dx = avgpool_grad_vm(x_shape_nchw, dout, mean_matrix, kernel_matrix)
             return (dx,)