Allow nodes to have a 'debug' behaviour for DebugMode.

theano/compile/debugmode.py

@@ -1883,8 +1883,10 @@ class _Linker(gof.link.LocalLinker):
                 if new_node is not None:
                     node = new_node
 
+            debug = hasattr(node.op, 'debug_perform')
+
             try:
-                if not self.maker.mode.check_c_code:
+                if not self.maker.mode.check_c_code or debug:
                     raise utils.MethodNotDefined()
                 # Ops that do not inherit from gof.op.Op don't have certain
                 # methods defined that the CLinker expects (Scan is an
@@ -1902,18 +1904,18 @@ class _Linker(gof.link.LocalLinker):
             # Pure ops don't really have a perform ( or their perform just
             # raises an not implemented exception), so in those cases we
             # consider that we don't have a python implementation
-            if (self.maker.mode.check_py_code or thunks_c[-1] is None) and \
-               node.op.perform.__code__ != gof.op.PureOp.perform.__code__:
+            if (((self.maker.mode.check_py_code or thunks_c[-1] is None) and
+                 node.op.perform.__code__ != gof.op.PureOp.perform.__code__) or
+                    debug):
                 thunk = node.op.make_py_thunk(node, storage_map, compute_map,
-                                              no_recycling)
+                                              no_recycling, debug=debug)
                 thunks_py.append(thunk)
             else:
                 thunks_py.append(None)
 
             if not self.maker.mode.check_c_code and thunks_py[-1] is None:
-                _logger.warn(
-                    "Op %s don't have a perform, forcing check of the c code" %
-                    node.op)
+                _logger.warn("Op %s doesn't have a perform, "
+                             "forcing check of the C code" % node.op)
                 thunk = node.op.make_c_thunk(node, storage_map, compute_map,
                                              no_recycling)
                 thunks_c[-1] = thunk

theano/gof/cc.py

@@ -1186,11 +1186,13 @@ class CLinker(link.Linker):
             List of lists of length 1. In order to use
             the thunk returned by __compile__, the inputs must be put in
             that storage. If None, storage will be allocated.
-        @param output_storage: list of lists of length 1. The thunk returned
-            by __compile__ will put the variables of the computation in these
-            lists. If None, storage will be allocated.
-        @param storage_map: dict that map variables to storages. This is used
-            when you need to customize the storage of this thunk.
+        output_storage: list of lists of length 1.
+            The thunk returned by __compile__ will put the variables
+            of the computation in these lists. If None, storage will
+            be allocated.
+        storage_map: dict that map variables to storages.
+            This is used when you need to customize the storage of
+            this thunk.
 
         Returns: thunk, input_storage, output_storage
 

theano/gof/op.py

@@ -890,7 +890,8 @@ class Op(utils.object2, PureOp, CLinkerOp):
         rval.lazy = False
         return rval
 
-    def make_py_thunk(self, node, storage_map, compute_map, no_recycling):
+    def make_py_thunk(self, node, storage_map, compute_map, no_recycling,
+                      debug=False):
         """
         Like make_thunk() but only makes python thunks.
 
@@ -898,6 +899,9 @@ class Op(utils.object2, PureOp, CLinkerOp):
         node_input_storage = [storage_map[r] for r in node.inputs]
         node_output_storage = [storage_map[r] for r in node.outputs]
 
+        if debug:
+            p = node.op.debug_perform
+        else:
             p = node.op.perform
 
         params = node.run_params()