sim: clean up child handling

The old code for handling SimObject children was kind of messy,
with children stored both in _values and _children, and
inconsistent and potentially buggy handling of SimObject
vectors.  Now children are always stored in _children, and
SimObject vectors are consistently handled using the
SimObjectVector class.

Also, by deferring the parenting of SimObject-valued parameters
until the end (instead of doing it at assignment), we eliminate
the hole where one could assign a vector of SimObjects to a
parameter then append to that vector, with the appended objects
never getting parented properly.

This patch induces small stats changes in tests with data races
due to changes in the object creation & initialization order.
The new code does object vectors in order and so should be more
stable.

src/python/m5/params.py

@@ -49,6 +49,7 @@ import datetime
 import re
 import sys
 import time
+import math
 
 import proxy
 import ticks
@@ -178,10 +179,42 @@ class VectorParamValue(list):
     def unproxy(self, base):
         return [v.unproxy(base) for v in self]
 
-class SimObjVector(VectorParamValue):
-    def print_ini(self, ini_file):
+class SimObjectVector(VectorParamValue):
+    # support clone operation
+    def __call__(self, **kwargs):
+        return SimObjectVector([v(**kwargs) for v in self])
+
+    def clear_parent(self, old_parent):
         for v in self:
-            v.print_ini(ini_file)
+            v.clear_parent(old_parent)
+
+    def set_parent(self, parent, name):
+        if len(self) == 1:
+            self[0].set_parent(parent, name)
+        else:
+            width = int(math.ceil(math.log(len(self))/math.log(10)))
+            for i,v in enumerate(self):
+                v.set_parent(parent, "%s%0*d" % (name, width, i))
+
+    def get_parent(self):
+        parent_set = set(v._parent for v in self)
+        if len(parent_set) != 1:
+            raise RuntimeError, \
+                  "SimObjectVector elements have inconsistent parent value."
+        return parent_set.pop()
+
+    # return 'cpu0 cpu1' etc. for print_ini()
+    def get_name(self):
+        return ' '.join([v._name for v in self])
+
+    # By iterating through the constituent members of the vector here
+    # we can nicely handle iterating over all a SimObject's children
+    # without having to provide lots of special functions on
+    # SimObjectVector directly.
+    def descendants(self):
+        for v in self:
+            for obj in v.descendants():
+                yield obj
 
 class VectorParamDesc(ParamDesc):
     file_ext = 'vptype'
@@ -197,7 +230,7 @@ class VectorParamDesc(ParamDesc):
             tmp_list = [ ParamDesc.convert(self, value) ]
 
         if isSimObjectSequence(tmp_list):
-            return SimObjVector(tmp_list)
+            return SimObjectVector(tmp_list)
         else:
             return VectorParamValue(tmp_list)