stats: create an enable phase, and a prepare phase.

Enable more or less takes the place of check, but also allows stats to
do some other configuration.  Prepare moves all of the code that readies
a stat for dumping into a separate function in preparation for supporting
serialization of certain pieces of statistics data.
While we're at it, clean up the visitor code and some of the python code.

src/python/m5/core.py

@@ -27,7 +27,14 @@
 # Authors: Nathan Binkert
 
 import internal
+from internal.core import initAll, regAllStats
 
 def setOutputDir(dir):
     internal.core.setOutputDir(dir)
 
+def initAll():
+    internal.core.initAll()
+
+def regAllStats():
+    internal.core.regAllStats()
+

src/python/m5/simulate.py

@@ -33,6 +33,8 @@ import sys
 
 # import the SWIG-wrapped main C++ functions
 import internal
+import core
+import stats
 from main import options
 import SimObject
 import ticks
@@ -52,23 +54,23 @@ def instantiate(root):
         ini_file.close()
 
     # Initialize the global statistics
-    internal.stats.initSimStats()
+    stats.initSimStats()
 
     # Create the C++ sim objects and connect ports
     root.createCCObject()
     root.connectPorts()
 
     # Do a second pass to finish initializing the sim objects
-    internal.core.initAll()
+    core.initAll()
 
     # Do a third pass to initialize statistics
-    internal.core.regAllStats()
+    core.regAllStats()
 
-    # Check to make sure that the stats package is properly initialized
-    internal.stats.check()
+    # We're done registering statistics.  Enable the stats package now.
+    stats.enable()
 
     # Reset to put the stats in a consistent state.
-    internal.stats.reset()
+    stats.reset()
 
 def doDot(root):
     dot = pydot.Dot()

src/python/m5/stats.py

@@ -28,9 +28,6 @@
 
 import internal
 
-from internal.stats import dump
-from internal.stats import initSimStats
-from internal.stats import reset
 from internal.stats import StatEvent as event
 
 def initText(filename, desc=True, compat=True):
@@ -44,3 +41,19 @@ def initMySQL(host, database, user='', passwd='', project='test', name='test',
 
     internal.stats.initMySQL(host, database, user, passwd, project, name,
                              sample)
+
+def initSimStats():
+    internal.stats.initSimStats()
+
+def enable():
+    internal.stats.enable()
+
+def dump():
+    # Currently prepare happens in the dump, but we should maybe move
+    # that out.
+
+    #internal.stats.prepare()
+    internal.stats.dump()
+
+def reset():
+    internal.stats.reset()

src/python/swig/stats.i

@@ -48,7 +48,8 @@ void initMySQL(std::string host, std::string database, std::string user,
 
 void StatEvent(bool dump, bool reset, Tick when = curTick, Tick repeat = 0);
 
-void check();
+void enable();
+void prepare();
 void dump();
 void reset();