mem: Rename Bus to XBar to better reflect its behaviour

This patch changes the name of the Bus classes to XBar to better
reflect the actual timing behaviour. The actual instances in the
config scripts are not renamed, and remain as e.g. iobus or membus.

As part of this renaming, the code has also been clean up slightly,
making use of range-based for loops and tidying up some comments. The
only changes outside the bus/crossbar code is due to the delay
variables in the packet.

--HG--
rename : src/mem/Bus.py => src/mem/XBar.py
rename : src/mem/coherent_bus.cc => src/mem/coherent_xbar.cc
rename : src/mem/coherent_bus.hh => src/mem/coherent_xbar.hh
rename : src/mem/noncoherent_bus.cc => src/mem/noncoherent_xbar.cc
rename : src/mem/noncoherent_bus.hh => src/mem/noncoherent_xbar.hh
rename : src/mem/bus.cc => src/mem/xbar.cc
rename : src/mem/bus.hh => src/mem/xbar.hh

src/python/m5/params.py

@@ -1870,7 +1870,7 @@ class SlavePort(Port):
             raise TypeError, 'wrong number of arguments'
 
 # VectorPort description object.  Like Port, but represents a vector
-# of connections (e.g., as on a Bus).
+# of connections (e.g., as on a XBar).
 class VectorPort(Port):
     def __init__(self, *args):
         self.isVec = True

src/python/m5/util/dot_writer.py

@@ -173,7 +173,7 @@ def dot_create_node(simNode, full_path, label):
 class NodeType:
     SYS = 0
     CPU = 1
-    BUS = 2
+    XBAR = 2
     MEM = 3
     DEV = 4
     OTHER = 5
@@ -190,8 +190,8 @@ def get_node_type(simNode):
     elif 'PioDevice' in dir(m5.objects) and \
             isinstance(simNode, m5.objects.PioDevice):
         return NodeType.DEV
-    elif isinstance(simNode, m5.objects.BaseBus):
-        return NodeType.BUS
+    elif isinstance(simNode, m5.objects.BaseXBar):
+        return NodeType.XBAR
     elif isinstance(simNode, m5.objects.AbstractMemory):
         return NodeType.MEM
     else:
@@ -205,7 +205,7 @@ def get_type_colour(nodeType):
         return (228, 231, 235)
     elif nodeType == NodeType.CPU:
         return (187, 198, 217)
-    elif nodeType == NodeType.BUS:
+    elif nodeType == NodeType.XBAR:
         return (111, 121, 140)
     elif nodeType == NodeType.MEM:
         return (94, 89, 88)