cache: coherence protocol enhancements & bug fixes

Allow lower-level caches (e.g., L2 or L3) to pass exclusive
copies to higher levels (e.g., L1).  This eliminates a lot
of unnecessary upgrade transactions on read-write sequences
to non-shared data.

Also some cleanup of MSHR coherence handling and multiple
bug fixes.

1 files changed, 23 insertions, 3 deletions

diff --git a/src/mem/cache/mshr.hh b/src/mem/cache/mshr.hh
index 26eef2cac..9b55e70ef 100644
--- a/src/mem/cache/mshr.hh
+++ b/src/mem/cache/mshr.hh
@@ -134,8 +134,28 @@ class MSHR : public Packet::SenderState, public Printable
 
     bool downstreamPending;
 
-    bool pendingInvalidate;
-    bool pendingShared;
+    /** The pending* and post* flags are only valid if inService is
+     *  true.  Using the accessor functions lets us detect if these
+     *  flags are accessed improperly.
+     */
+
+    /** Will we have a dirty copy after this request? */
+    bool pendingDirty;
+    bool isPendingDirty() const {
+        assert(inService); return pendingDirty;
+    }
+
+    /** Did we snoop an invalidate while waiting for data? */
+    bool postInvalidate;
+    bool hasPostInvalidate() const {
+        assert(inService); return postInvalidate;
+    }
+
+    /** Did we snoop a read while waiting for data? */
+    bool postDowngrade;
+    bool hasPostDowngrade() const {
+        assert(inService); return postDowngrade;
+    }
 
     /** Thread number of the miss. */
     ThreadID threadNum;
@@ -180,7 +200,7 @@ public:
     void allocate(Addr addr, int size, PacketPtr pkt,
                   Tick when, Counter _order);
 
-    bool markInService();
+    bool markInService(PacketPtr pkt);
 
     void clearDownstreamPending();