cpu: fix simInsts and simOps not resetting (#1615)

This PR fixes the bug where simInsts and simOps don't reset when
m5.stats.reset() is called. The stats hostInstRate and hostOpRate are
affected by this change as well, as they depend on simInsts and simOps
respectively.

This is related to issue 1443 linked
[here](https://github.com/gem5/gem5/issues/1443).

src/cpu/base.cc

@@ -859,13 +859,13 @@ BaseCPU::GlobalStats::GlobalStats(statistics::Group *parent)
              "Simulator op (including micro ops) rate (op/s)")
 {
     simInsts
-        .functor(BaseCPU::numSimulatedInsts)
+        .functor(BaseCPU::GlobalStats::numSimulatedInsts)
         .precision(0)
         .prereq(simInsts)
         ;
 
     simOps
-        .functor(BaseCPU::numSimulatedOps)
+        .functor(BaseCPU::GlobalStats::numSimulatedOps)
         .precision(0)
         .prereq(simOps)
         ;

src/cpu/base.hh

@@ -156,6 +156,30 @@ class BaseCPU : public ClockedObject
 
         statistics::Formula hostInstRate;
         statistics::Formula hostOpRate;
+
+        Counter previousInsts = 0;
+        Counter previousOps = 0;
+
+        static Counter
+        numSimulatedInsts()
+        {
+            return totalNumSimulatedInsts() - (globalStats->previousInsts);
+        }
+
+        static Counter
+        numSimulatedOps()
+        {
+            return totalNumSimulatedOps() - (globalStats->previousOps);
+        }
+
+        void
+        resetStats() override
+        {
+            previousInsts = totalNumSimulatedInsts();
+            previousOps = totalNumSimulatedOps();
+
+            statistics::Group::resetStats();
+        }
     };
 
     /**
@@ -609,7 +633,7 @@ class BaseCPU : public ClockedObject
 
     static int numSimulatedCPUs() { return cpuList.size(); }
     static Counter
-    numSimulatedInsts()
+    totalNumSimulatedInsts()
     {
         Counter total = 0;
 
@@ -621,7 +645,7 @@ class BaseCPU : public ClockedObject
     }
 
     static Counter
-    numSimulatedOps()
+    totalNumSimulatedOps()
     {
         Counter total = 0;
 

src/cpu/o3/probe/elastic_trace.cc

@@ -122,7 +122,7 @@ ElasticTrace::regEtraceListeners()
 {
     assert(!allProbesReg);
     inform("@%llu: No. of instructions committed = %llu, registering elastic"
-        " probe listeners", curTick(), cpu->numSimulatedInsts());
+        " probe listeners", curTick(), cpu->totalNumSimulatedInsts());
     // Create new listeners: provide method to be called upon a notify() for
     // each probe point.
     listeners.push_back(new ProbeListenerArg<ElasticTrace, RequestPtr>(this,