mem: Add predecessor to SenderState base class

This patch adds a predecessor field to the SenderState base class to
make the process of linking them up more uniform, and enable a
traversal of the stack without knowing the specific type of the
subclasses.

There are a number of simplifications done as part of changing the
SenderState, particularly in the RubyTest.

1 files changed, 5 insertions, 3 deletions

diff --git a/src/mem/ruby/system/Sequencer.cc b/src/mem/ruby/system/Sequencer.cc
index 1cdd6d806..f00f8407a 100644
--- a/src/mem/ruby/system/Sequencer.cc
+++ b/src/mem/ruby/system/Sequencer.cc
@@ -530,11 +530,13 @@ Sequencer::hitCallback(SequencerRequest* srequest,
     // Note: RubyPort will access it's sender state before the
     // RubyTester.
     if (m_usingRubyTester) {
-        RubyPort::SenderState *requestSenderState =
+        RubyPort::SenderState *reqSenderState =
             safe_cast<RubyPort::SenderState*>(pkt->senderState);
+        // @todo This is a dangerous assumption on nothing else
+        // modifying the senderState
         RubyTester::SenderState* testerSenderState =
-            safe_cast<RubyTester::SenderState*>(requestSenderState->saved);
-        testerSenderState->subBlock->mergeFrom(data);
+            safe_cast<RubyTester::SenderState*>(reqSenderState->predecessor);
+        testerSenderState->subBlock.mergeFrom(data);
     }
 
     delete srequest;