sim: fold checkpoint restore code into instantiate()

The separate restoreCheckpoint() call is gone; just pass
the checkpoint dir as an optional arg to instantiate().
This change is a precursor to some more extensive
reworking of the startup code.

src/python/m5/simulate.py

@@ -46,7 +46,7 @@ MaxTick = 2**63 - 1
 
 # The final hook to generate .ini files.  Called from the user script
 # once the config is built.
-def instantiate():
+def instantiate(ckpt_dir=None):
     root = objects.Root.getInstance()
 
     if not root:
@@ -86,6 +86,11 @@ def instantiate():
     # We're done registering statistics.  Enable the stats package now.
     stats.enable()
 
+    # Restore checkpoint (if any)
+    if ckpt_dir:
+        internal.core.unserializeAll(ckpt_dir)
+        need_resume.append(root)
+
     # Reset to put the stats in a consistent state.
     stats.reset()
 
@@ -160,13 +165,6 @@ def checkpoint(dir):
     internal.core.serializeAll(dir)
     resume(root)
 
-def restoreCheckpoint(dir):
-    root = objects.Root.getInstance()
-    print "Restoring from checkpoint"
-    internal.core.unserializeAll(dir)
-    need_resume.append(root)
-    stats.reset()
-
 def changeToAtomic(system):
     if not isinstance(system, (objects.Root, objects.System)):
         raise TypeError, "Parameter of type '%s'.  Must be type %s or %s." % \