mem: Make cache terminology easier to understand

This patch changes the name of a bunch of packet flags and MSHR member
functions and variables to make the coherency protocol easier to
understand. In addition the patch adds and updates lots of
descriptions, explicitly spelling out assumptions.

The following name changes are made:

* the packet memInhibit flag is renamed to cacheResponding

* the packet sharedAsserted flag is renamed to hasSharers

* the packet NeedsExclusive attribute is renamed to NeedsWritable

* the packet isSupplyExclusive is renamed responderHadWritable

* the MSHR pendingDirty is renamed to pendingModified

The cache states, Modified, Owned, Exclusive, Shared are also called
out in the cache and MSHR code to make it easier to understand.

1 files changed, 5 insertions, 3 deletions

diff --git a/src/mem/tport.cc b/src/mem/tport.cc
index 9f9403a22..b80c2d93a 100644
--- a/src/mem/tport.cc
+++ b/src/mem/tport.cc
@@ -63,9 +63,11 @@ bool
 SimpleTimingPort::recvTimingReq(PacketPtr pkt)
 {
     // the SimpleTimingPort should not be used anywhere where there is
-    // a need to deal with inhibited packets
-    if (pkt->memInhibitAsserted())
-        panic("SimpleTimingPort should never see an inhibited request\n");
+    // a need to deal with snoop responses and their flow control
+    // requirements
+    if (pkt->cacheResponding())
+        panic("SimpleTimingPort should never see packets with the "
+              "cacheResponding flag set\n");
 
     bool needsResponse = pkt->needsResponse();
     Tick latency = recvAtomic(pkt);