Add checking for inputs in new NanGuardMode.

theano/compile/nanguardmode.py

@@ -71,7 +71,7 @@ def contains_nan(arr, node=None):
     elif arr.size == 0:
         return False
     elif cuda.cuda_available and isinstance(arr, cuda.CudaNdarray):
-        if (hasattr(theano.sandbox, 'rng_mrg') and
+        if (node and hasattr(theano.sandbox, 'rng_mrg') and
             isinstance(
                 node.op,
                 # It store ints in float container
@@ -115,7 +115,7 @@ def contains_inf(arr, node=None):
     elif arr.size == 0:
         return False
     elif cuda.cuda_available and isinstance(arr, cuda.CudaNdarray):
-        if (hasattr(theano.sandbox, 'rng_mrg') and
+        if (node and hasattr(theano.sandbox, 'rng_mrg') and
             isinstance(
                 node.op,
                 # It store ints in float container
@@ -251,10 +251,14 @@ class NanGuardMode(Mode):
                     print('Big value detected', file=sio)
                     error = True
             if error:
-                print("NanGuardMode found an error in the"
-                      " output of a node in this variable:", file=sio)
-                print(theano.printing.debugprint(nd, file='str'), file=sio)
-                msg = sio.getvalue()
+                if nd:
+                    print("NanGuardMode found an error in the "
+                          "output of a node in this variable:", file=sio)
+                    print(theano.printing.debugprint(nd, file='str'), file=sio)
+                    msg = sio.getvalue()
+                else:
+                    print("NanGuardMode found an error in an input of the "
+                          "graph.", file=sio)
                 if config.NanGuardMode.action == 'raise':
                     raise AssertionError(msg)
                 elif config.NanGuardMode.action == 'pdb':
@@ -265,25 +269,15 @@ class NanGuardMode(Mode):
                     logger.error(msg)
 
         def nan_check(node, thunk, storage_map, compute_map):
-            """
-            Runs `fn` while checking its inputs and outputs for NaNs / Infs.
-
-            Parameters
-            ----------
-            node : theano.gof.Apply
-                The Apply node currently being executed.
-            thunk : callable
-                The thunk to execute for this Apply node.
-            storage_map : dict
-                The mapping of variables to storage cells.
-            compute_map : dict
-                The mapping to get the computed state of the nodes. (ignored)
-
-            """
             for var in node.outputs:
                 if getattr(var.tag, 'nan_guard_mode_check', True):
                     do_check_on(storage_map[var][0], node)
 
-        wrap_linker = theano.gof.vm.VM_Linker(callback=nan_check)
+        def nan_check_input(var, value):
+            if getattr(var.tag, 'nan_guard_mode_check', True):
+                do_check_on(value, None)
+
+        wrap_linker = theano.gof.vm.VM_Linker(callback=nan_check,
+                                              callback_input=nan_check_input)
         super(NanGuardMode, self).__init__(wrap_linker,
                                            optimizer=self.provided_optimizer)