Report stale sample count and percentage

Summary: This diff adds extra reporting of total number of stale branch samples for the binary.

(cherry picked from FBD22304965)

bolt/src/BinaryFunction.h

@@ -340,6 +340,9 @@ private:
   /// Profile match ratio.
   float ProfileMatchRatio{0.0f};
 
+  /// Raw branch count for this function in the profile
+  uint64_t RawBranchCount{0};
+
   /// Indicates the type of profile the function is using.
   uint16_t ProfileFlags{PF_NONE};
 
@@ -1956,6 +1959,10 @@ public:
     return ExecutionCount;
   }
 
+  /// Return the raw profile information about the number of branch
+  /// executions corresponding to this function.
+  uint64_t getRawBranchCount() const { return RawBranchCount; }
+
   /// Return the execution count for functions with known profile.
   /// Return 0 if the function has no profile.
   uint64_t getKnownExecutionCount() const {

bolt/src/DataReader.cpp

@@ -119,6 +119,16 @@ void FuncBranchData::appendFrom(const FuncBranchData &FBD, uint64_t Offset) {
   }
 }
 
+uint64_t FuncBranchData::getNumExecutedBranches() const {
+  uint64_t ExecutedBranches{0};
+  for (const auto &BI : Data) {
+    auto BranchCount = BI.Branches;
+    assert(BranchCount >= 0 && "branch execution count should not be negative");
+    ExecutedBranches += BranchCount;
+  }
+  return ExecutedBranches;
+}
+
 void SampleInfo::mergeWith(const SampleInfo &SI) {
   Hits += SI.Hits;
 }
@@ -437,10 +447,12 @@ void DataReader::matchProfileData(BinaryFunction &BF) {
   FuncBranchData *FBD = getBranchData(BF);
   if (FBD) {
     BF.ProfileMatchRatio = evaluateProfileData(BF, *FBD);
+    BF.RawBranchCount = FBD->getNumExecutedBranches();
     if (BF.ProfileMatchRatio == 1.0f) {
       if (fetchProfileForOtherEntryPoints(BF)) {
         BF.ProfileMatchRatio = evaluateProfileData(BF, *FBD);
         BF.ExecutionCount = FBD->ExecutionCount;
+        BF.RawBranchCount = FBD->getNumExecutedBranches();
       }
       return;
     }

bolt/src/DataReader.h

@@ -147,6 +147,10 @@ struct FuncBranchData {
   /// from the entry of this function.
   void appendFrom(const FuncBranchData &FBD, uint64_t Offset);
 
+  /// Returns the total number of executed branches in this function
+  /// by counting the number of executed branches for each BranchInfo
+  uint64_t getNumExecutedBranches() const;
+
   /// Aggregation helpers
   DenseMap<uint64_t, DenseMap<uint64_t, size_t>> IntraIndex;
   DenseMap<uint64_t, DenseMap<Location, size_t>> InterIndex;

bolt/src/Passes/BinaryPasses.cpp

@@ -1259,6 +1259,8 @@ PrintProgramStats::runOnFunctions(BinaryContext &BC) {
   uint64_t NumStaleProfileFunctions{0};
   uint64_t NumNonSimpleProfiledFunctions{0};
   uint64_t NumUnknownControlFlowFunctions{0};
+  uint64_t TotalSampleCount{0};
+  uint64_t StaleSampleCount{0};
   std::vector<BinaryFunction *> ProfiledFunctions;
   const char *StaleFuncsHeader = "BOLT-INFO: Functions with stale profile:\n";
   for (auto &BFI : BC.getBinaryFunctions()) {
@@ -1289,6 +1291,9 @@ PrintProgramStats::runOnFunctions(BinaryContext &BC) {
     if (!Function.hasProfile())
       continue;
 
+    auto SampleCount = Function.getRawBranchCount();
+    TotalSampleCount += SampleCount;
+
     if (Function.hasValidProfile()) {
       ProfiledFunctions.push_back(&Function);
     } else {
@@ -1298,6 +1303,7 @@ PrintProgramStats::runOnFunctions(BinaryContext &BC) {
         outs() << "  " << Function << '\n';
       }
       ++NumStaleProfileFunctions;
+      StaleSampleCount += SampleCount;
     }
   }
   BC.NumProfiledFuncs = ProfiledFunctions.size();
@@ -1317,16 +1323,27 @@ PrintProgramStats::runOnFunctions(BinaryContext &BC) {
   if (NumStaleProfileFunctions) {
     const float PctStale =
       NumStaleProfileFunctions / (float) NumAllProfiledFunctions * 100.0f;
-    if (PctStale > opts::StaleThreshold) {
-      errs() << "BOLT-ERROR: ";
-    } else {
-      errs() << "BOLT-WARNING: ";
-    }
+    auto printErrorOrWarning = [&]() {
+      if (PctStale > opts::StaleThreshold) {
+        errs() << "BOLT-ERROR: ";
+      } else {
+        errs() << "BOLT-WARNING: ";
+      }
+    };
+    printErrorOrWarning();
     errs() << NumStaleProfileFunctions
            << format(" (%.1f%% of all profiled)", PctStale)
            << " function" << (NumStaleProfileFunctions == 1 ? "" : "s")
            << " have invalid (possibly stale) profile."
               " Use -report-stale to see the list.\n";
+    if (TotalSampleCount > 0) {
+      printErrorOrWarning();
+      errs() << StaleSampleCount << " out of " << TotalSampleCount
+             << " samples in the binary ("
+             << format("%.1f", ((100.0f * StaleSampleCount) / TotalSampleCount))
+             << "%) belong to functions with invalid"
+                " (possibly stale) profile.\n";
+    }
     if (PctStale > opts::StaleThreshold) {
       errs() << "BOLT-ERROR: stale functions exceed specified threshold of "
              << opts::StaleThreshold << "%. Exiting.\n";