MEM: Introduce the master/slave port sub-classes in C++

This patch introduces the notion of a master and slave port in the C++
code, thus bringing the previous classification from the Python
classes into the corresponding simulation objects and memory objects.

The patch enables us to classify behaviours into the two bins and add
assumptions and enfore compliance, also simplifying the two
interfaces. As a starting point, isSnooping is confined to a master
port, and getAddrRanges to slave ports. More of these specilisations
are to come in later patches.

The getPort function is not getMasterPort and getSlavePort, and
returns a port reference rather than a pointer as NULL would never be
a valid return value. The default implementation of these two
functions is placed in MemObject, and calls fatal.

The one drawback with this specific patch is that it requires some
code duplication, e.g. QueuedPort becomes QueuedMasterPort and
QueuedSlavePort, and BusPort becomes BusMasterPort and BusSlavePort
(avoiding multiple inheritance). With the later introduction of the
port interfaces, moving the functionality outside the port itself, a
lot of the duplicated code will disappear again.

1 files changed, 30 insertions, 45 deletions

diff --git a/src/cpu/base.cc b/src/cpu/base.cc
index 5d5f704db..d01dcbef3 100644
--- a/src/cpu/base.cc
+++ b/src/cpu/base.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011 ARM Limited
+ * Copyright (c) 2011-2012 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -299,19 +299,19 @@ BaseCPU::regStats()
         threadContexts[0]->regStats(name());
 }
 
-Port *
-BaseCPU::getPort(const string &if_name, int idx)
+MasterPort &
+BaseCPU::getMasterPort(const string &if_name, int idx)
 {
     // Get the right port based on name. This applies to all the
     // subclasses of the base CPU and relies on their implementation
     // of getDataPort and getInstPort. In all cases there methods
     // return a CpuPort pointer.
     if (if_name == "dcache_port")
-        return &getDataPort();
+        return getDataPort();
     else if (if_name == "icache_port")
-        return &getInstPort();
+        return getInstPort();
     else
-        panic("CPU %s has no port named %s\n", name(), if_name);
+        return MemObject::getMasterPort(if_name, idx);
 }
 
 Tick
@@ -381,8 +381,6 @@ BaseCPU::switchOut()
 void
 BaseCPU::takeOverFrom(BaseCPU *oldCPU)
 {
-    CpuPort &ic = getInstPort();
-    CpuPort &dc = getDataPort();
     assert(threadContexts.size() == oldCPU->threadContexts.size());
 
     _cpuId = oldCPU->cpuId();
@@ -407,24 +405,21 @@ BaseCPU::takeOverFrom(BaseCPU *oldCPU)
             ThreadContext::compare(oldTC, newTC);
         */
 
-        Port  *old_itb_port, *old_dtb_port, *new_itb_port, *new_dtb_port;
-        old_itb_port = oldTC->getITBPtr()->getPort();
-        old_dtb_port = oldTC->getDTBPtr()->getPort();
-        new_itb_port = newTC->getITBPtr()->getPort();
-        new_dtb_port = newTC->getDTBPtr()->getPort();
+        MasterPort *old_itb_port = oldTC->getITBPtr()->getMasterPort();
+        MasterPort *old_dtb_port = oldTC->getDTBPtr()->getMasterPort();
+        MasterPort *new_itb_port = newTC->getITBPtr()->getMasterPort();
+        MasterPort *new_dtb_port = newTC->getDTBPtr()->getMasterPort();
 
         // Move over any table walker ports if they exist
         if (new_itb_port && !new_itb_port->isConnected()) {
             assert(old_itb_port);
-            Port *peer = old_itb_port->getPeer();;
-            new_itb_port->setPeer(peer);
-            peer->setPeer(new_itb_port);
+            SlavePort &slavePort = old_itb_port->getSlavePort();
+            new_itb_port->bind(slavePort);
         }
         if (new_dtb_port && !new_dtb_port->isConnected()) {
             assert(old_dtb_port);
-            Port *peer = old_dtb_port->getPeer();;
-            new_dtb_port->setPeer(peer);
-            peer->setPeer(new_dtb_port);
+            SlavePort &slavePort = old_dtb_port->getSlavePort();
+            new_dtb_port->bind(slavePort);
         }
 
         // Checker whether or not we have to transfer CheckerCPU
@@ -432,26 +427,25 @@ BaseCPU::takeOverFrom(BaseCPU *oldCPU)
         CheckerCPU *oldChecker = oldTC->getCheckerCpuPtr();
         CheckerCPU *newChecker = newTC->getCheckerCpuPtr();
         if (oldChecker && newChecker) {
-            Port *old_checker_itb_port, *old_checker_dtb_port;
-            Port *new_checker_itb_port, *new_checker_dtb_port;
-
-            old_checker_itb_port = oldChecker->getITBPtr()->getPort();
-            old_checker_dtb_port = oldChecker->getDTBPtr()->getPort();
-            new_checker_itb_port = newChecker->getITBPtr()->getPort();
-            new_checker_dtb_port = newChecker->getDTBPtr()->getPort();
+            MasterPort *old_checker_itb_port =
+                oldChecker->getITBPtr()->getMasterPort();
+            MasterPort *old_checker_dtb_port =
+                oldChecker->getDTBPtr()->getMasterPort();
+            MasterPort *new_checker_itb_port =
+                newChecker->getITBPtr()->getMasterPort();
+            MasterPort *new_checker_dtb_port =
+                newChecker->getDTBPtr()->getMasterPort();
 
             // Move over any table walker ports if they exist for checker
             if (new_checker_itb_port && !new_checker_itb_port->isConnected()) {
                 assert(old_checker_itb_port);
-                Port *peer = old_checker_itb_port->getPeer();;
-                new_checker_itb_port->setPeer(peer);
-                peer->setPeer(new_checker_itb_port);
+                SlavePort &slavePort = old_checker_itb_port->getSlavePort();;
+                new_checker_itb_port->bind(slavePort);
             }
             if (new_checker_dtb_port && !new_checker_dtb_port->isConnected()) {
                 assert(old_checker_dtb_port);
-                Port *peer = old_checker_dtb_port->getPeer();;
-                new_checker_dtb_port->setPeer(peer);
-                peer->setPeer(new_checker_dtb_port);
+                SlavePort &slavePort = old_checker_dtb_port->getSlavePort();;
+                new_checker_dtb_port->bind(slavePort);
             }
         }
     }
@@ -470,16 +464,12 @@ BaseCPU::takeOverFrom(BaseCPU *oldCPU)
     // Connect new CPU to old CPU's memory only if new CPU isn't
     // connected to anything.  Also connect old CPU's memory to new
     // CPU.
-    if (!ic.isConnected()) {
-        Port *peer = oldCPU->getInstPort().getPeer();
-        ic.setPeer(peer);
-        peer->setPeer(&ic);
+    if (!getInstPort().isConnected()) {
+        getInstPort().bind(oldCPU->getInstPort().getSlavePort());
     }
 
-    if (!dc.isConnected()) {
-        Port *peer = oldCPU->getDataPort().getPeer();
-        dc.setPeer(peer);
-        peer->setPeer(&dc);
+    if (!getDataPort().isConnected()) {
+        getDataPort().bind(oldCPU->getDataPort().getSlavePort());
     }
 }
 
@@ -568,8 +558,3 @@ BaseCPU::CpuPort::recvFunctional(PacketPtr pkt)
     // long term this should never be called, but that assumed a split
     // into master/slave and request/response.
 }
-
-void
-BaseCPU::CpuPort::recvRangeChange()
-{
-}