Performance issue in the definition of cudnn_gru, MRC/BiDAF/layers.py(P1)

[DLPerf]

Hello, I found a performance issue in the definition of cudnn_gru, MRC/BiDAF/layers.py, tf.zeros([1, batch_size, num_units]) will be created repeatedly during program execution, resulting in reduced efficiency. I think it should be created before the loop.

The same issue exist in :

• tf.zeros in line 97;
• tf.zeros in line 149 and 150;
• tf.zeros in line 131 and 132;
• tf.zeros in line 187 and 188;
• tf.zeros in line 133 and 134;
• tf.zeros in line 186 and 187;
• tf.zeros in line 235 and 236;

Looking forward to your reply. Btw, I am very glad to create a PR to fix it if you are too busy.