cpu-o3:Add S3 prediction statistics to UBTB (#643)

* cpu-o3:Add S3 prediction statistics to UBTB

Change-Id: Ie0a9a32f0ffc5e41a8555954392a08f62b746dc2

* cpu-o3: Fix formatting in UBTBStats constructor for consistency

Change-Id: Iba74bbd15e4ab95e21b0fc36a0619831bc3b31a9

* cpu-o3: Enhance BTB entry update condition

Change-Id: Ieaadb337dcff060d1c5b7163c0c08b7a5aa17f24

* cpu-o3: Rename S3 prediction statistics for clarity in UBTB

Change-Id: I3abf8c61058cf8dc208985f596653964601aa212

* cpu-o3: mbtb removing unnecessary check for exeTaken

Change-Id: Ie28e857ea2a6f9b44b09259986a4e5980271ac7c

---------

Co-authored-by: Cao Jiaming <caojiaming@bosc.ac.cn>

Author: CJ362ff

src/cpu/pred/btb/btb_ubtb.cc

@@ -200,14 +200,20 @@ UBTB::replaceOldEntry(UBTBIter oldEntryIter, const BTBEntry &newTakenEntry, Addr
 void
 UBTB::updateUsingS3Pred(FullBTBPrediction &s3Pred)
 {
-    if (usingS3Pred) {
-        auto takenEntry = s3Pred.getTakenEntry();
-        auto startAddr = s3Pred.bbStart;
-        UBTBIter oldEntryIter = lastPred.hit_entry;
-        updateNewEntry(oldEntryIter, takenEntry, startAddr);
-    } else {
-        //using commit result to update ubtb
+    if (!usingS3Pred) {
+        return;
     }
+
+    auto takenEntry = s3Pred.getTakenEntry();
+    if (takenEntry.valid) {
+        ubtbStats.s3UpdateHits++;
+    }else {
+        ubtbStats.s3UpdateMisses++;
+    }
+    auto startAddr = s3Pred.bbStart;
+    UBTBIter oldEntryIter = lastPred.hit_entry;
+    updateNewEntry(oldEntryIter, takenEntry, startAddr);
+
 }
 
 
@@ -300,6 +306,8 @@ UBTB::update(const FetchStream &stream)
         if (!pred_hit_entry.valid || pred_hit_entry != stream.exeBranchInfo) {
             DPRINTF(UBTB, "update miss detected, pc %#lx, predTick %lu\n", stream.exeBranchInfo.pc, stream.predTick);
             ubtbStats.updateMiss++;
+        }else {
+            ubtbStats.updateHit++;
         }
     }
 
@@ -407,7 +415,9 @@ UBTB::UBTBStats::UBTBStats(statistics::Group *parent)
       ADD_STAT(predMiss, statistics::units::Count::get(), "misses encountered on prediction"),
       ADD_STAT(predHit, statistics::units::Count::get(), "hits encountered on prediction"),
       ADD_STAT(updateMiss, statistics::units::Count::get(), "misses encountered on update"),
-
+      ADD_STAT(updateHit, statistics::units::Count::get(), "hits encountered on update"),
+      ADD_STAT(s3UpdateHits, statistics::units::Count::get(), "hits encountered on S3 update"),
+      ADD_STAT(s3UpdateMisses, statistics::units::Count::get(), "misses encountered on S3 update"),
 
       ADD_STAT(allBranchHits, statistics::units::Count::get(),
                "all types of branches committed that was predicted hit"),

src/cpu/pred/btb/btb_ubtb.hh

@@ -286,6 +286,9 @@ class UBTB : public TimedBaseBTBPredictor
         statistics::Scalar predMiss;
         statistics::Scalar predHit;
         statistics::Scalar updateMiss;
+        statistics::Scalar updateHit;
+        statistics::Scalar s3UpdateHits;
+        statistics::Scalar s3UpdateMisses;
 
         // per branch statistics
         statistics::Scalar allBranchHits;