fix the div 0 errors in psroi_pool (PaddlePaddle#49965)

* fix the div 0 errors in psroi_pool

* fix case 7

* rool back sth.

python/paddle/fluid/tests/unittests/test_psroi_pool_op.py

@@ -339,6 +339,22 @@ def test_channel_error():
         self.assertRaises(ValueError, test_channel_error)
 
 
+class TestPSROIPoolZeroDivError(unittest.TestCase):
+    def setUp(self):
+        paddle.disable_static()
+        self.x = paddle.uniform([2, 490, 28, 28], dtype='float32')
+        self.boxes = paddle.to_tensor(
+            [[1, 5, 8, 10], [4, 2, 6, 7], [12, 12, 19, 21]], dtype='float32'
+        )
+        self.boxes_num = paddle.to_tensor([1, 2], dtype='int32')
+
+    def test_errors(self):
+        def test_zero_div_error():
+            paddle.vision.ops.psroi_pool(self.x, self.boxes, self.boxes_num, 0)
+
+        self.assertRaises(ValueError, test_zero_div_error)
+
+
 class TestPSROIPoolStaticAPI(unittest.TestCase):
     def setUp(self):
         paddle.enable_static()

python/paddle/vision/ops.py

@@ -1424,6 +1424,8 @@ def psroi_pool(x, boxes, boxes_num, output_size, spatial_scale=1.0, name=None):
         output_size = (output_size, output_size)
     pooled_height, pooled_width = output_size
     assert len(x.shape) == 4, "Input features with shape should be (N, C, H, W)"
+    if pooled_height * pooled_width == 0:
+        raise ValueError('output_size should not contain 0.')
     output_channels = int(x.shape[1] / (pooled_height * pooled_width))
     if in_dygraph_mode():
         return _C_ops.psroi_pool(