config: Fix for port references generated multiple times

SimObjects are expected to only generate one port reference per
port belonging to them.  There is a subtle bug with using "not"
here as a VectorPort is seen as not having a reference if it is
either None or empty as per Python docs sec 9.9 for Standard operators.
Intended behavior is to only check if we have not created the reference.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/python/m5/SimObject.py b/src/python/m5/SimObject.py
index 09145f498..8aa7260e7 100644
--- a/src/python/m5/SimObject.py
+++ b/src/python/m5/SimObject.py
@@ -698,7 +698,7 @@ class SimObject(object):
         # via __setattr__.  There is only ever one reference
         # object per port, but we create them lazily here.
         ref = self._port_refs.get(attr)
-        if not ref:
+        if ref == None:
             ref = self._ports[attr].makeRef(self)
             self._port_refs[attr] = ref
         return ref