mem-cache: add prefetcher listener for evictions

Listener to data update probe notifies prefetcher of evictions.
Prefetchers need to implement notifyEvict to make use of this
information.

Related JIRA:
https://gem5.atlassian.net/browse/GEM5-457
https://gem5.atlassian.net/browse/GEM5-1112

Change-Id: I052cfdeba1e40ede077554ada104522f6a0cb2c7
Signed-off-by: Tiago Mück <tiago.muck@arm.com>

src/mem/cache/prefetch/base.cc

@@ -92,6 +92,13 @@ Base::PrefetchListener::notify(const CacheAccessProbeArg &arg)
     }
 }
 
+void
+Base::PrefetchEvictListener::notify(const EvictionInfo &info)
+{
+    if (info.newData.empty())
+        parent.notifyEvict(info);
+}
+
 Base::Base(const BasePrefetcherParams &p)
     : ClockedObject(p), listeners(), system(nullptr), probeManager(nullptr),
       blkSize(p.block_size), lBlkSize(floorLog2(blkSize)),
@@ -274,6 +281,8 @@ Base::regProbeListeners()
                                                  "Fill", true, false));
         listeners.push_back(new PrefetchListener(*this, probeManager,
                                                  "Hit", false, false));
+        listeners.push_back(new PrefetchEvictListener(*this, probeManager,
+                                                 "Data Update"));
     }
 }
 

src/mem/cache/prefetch/base.hh

@@ -86,7 +86,20 @@ class Base : public ClockedObject
         const bool miss;
     };
 
-    std::vector<PrefetchListener *> listeners;
+    using EvictionInfo = CacheDataUpdateProbeArg;
+
+    class PrefetchEvictListener : public ProbeListenerArgBase<EvictionInfo>
+    {
+      public:
+        PrefetchEvictListener(Base &_parent, ProbeManager *pm,
+                              const std::string &name)
+            : ProbeListenerArgBase(pm, name), parent(_parent) {}
+        void notify(const EvictionInfo &info) override;
+      protected:
+        Base &parent;
+    };
+
+    std::vector<ProbeListener *> listeners;
 
   public:
 
@@ -381,6 +394,10 @@ class Base : public ClockedObject
     virtual void notifyFill(const CacheAccessProbeArg &acc)
     {}
 
+    /** Notify prefetcher of cache eviction */
+    virtual void notifyEvict(const EvictionInfo &info)
+    {}
+
     virtual PacketPtr getPacket() = 0;
 
     virtual Tick nextPrefetchReadyTime() const = 0;