Minor fixes

Author: wallento

riscvmodel/model.py

@@ -34,7 +34,7 @@ def reset(self, pc = 0):
         self.pc.set(pc)
 
     def __setattr__(self, key, value):
-        if key is "pc" and "pc_update" in self.__dict__:
+        if key == "pc" and "pc_update" in self.__dict__:
             self.pc_update.set(value)
         else:
             super().__setattr__(key, value)

riscvmodel/types.py

@@ -7,8 +7,6 @@ class InvalidImmediateException(Exception):
     """
     This exception is generated by Immediates for invalid values. It contains the message for the reason.
     """
-    pass
-
 
 class Immediate(object):
     """
@@ -280,7 +278,7 @@ def __init__(self, pc):
         self.pc = pc
 
     def __str__(self):
-        return "pc = {}".format(self.pc_update)
+        return "pc = {}".format(self.pc)
 
 
 class TraceRegister(Trace):