skip type/dtype check in dygraph mode, test=develop (#22915)

python/paddle/fluid/data_feeder.py

@@ -22,7 +22,7 @@ from six.moves import zip, range, xrange
 import multiprocessing
 import warnings
 
-from .framework import Variable, default_main_program, _current_expected_place
+from .framework import Variable, default_main_program, _current_expected_place, in_dygraph_mode
 from .framework import _cpu_num, _cuda_ids
 __all__ = ['DataFeeder']
 
@@ -81,6 +81,15 @@ def check_variable_and_dtype(input,
 
 
 def check_type(input, input_name, expected_type, op_name, extra_message=''):
+    # NOTE [ Why skip dynamic graph check ]:
+    # 1. If the input type / dtype of a layer is wrong, it will be reported
+    # directly on that line. User can easily print the relevant information
+    # on which line. It is easier to debug, so there is no need to check
+    # in dynamic graph mode.
+    # 2. Performance considerations. Because these checks are executed at
+    # each step in dynamic graph mode, it will bring a heavy performance burden.
+    if in_dygraph_mode():
+        return
     if not isinstance(input, expected_type):
         raise TypeError(
             "The type of '%s' in %s must be %s, but received %s. %s" %
@@ -92,6 +101,9 @@ def check_dtype(input_dtype,
                 expected_dtype,
                 op_name,
                 extra_message=''):
+    # See NOTE [ Why skip dynamic graph check ]
+    if in_dygraph_mode():
+        return
     if convert_dtype(input_dtype) in ['float16']:
         warnings.warn(
             "The data type of '%s' in %s only support float16 in GPU now. %s" %