[BOLT][NFC] Extract DataAggregator::parseLBRSample

bolt/include/bolt/Profile/DataAggregator.h

private:
   /// Prepare to parse data from a given perf script invocation.
   /// Returns an invocation exit code.
   int prepareToParse(StringRef Name, PerfProcessInfo &Process,
                      PerfProcessErrorCallbackTy Callback);
 
   /// Parse a single LBR entry as output by perf script -Fbrstack
   ErrorOr<LBREntry> parseLBREntry();
 
+  /// Parse LBR sample, returns the number of traces.
+  uint64_t parseLBRSample(const PerfBranchSample &Sample, bool NeedsSkylakeFix);
+
   /// Parse and pre-aggregate branch events.
   std::error_code parseBranchEvents();
 
   /// Process all branch events.
   void processBranchEvents();
 
   /// This member function supports generating data for AutoFDO LLVM tools.
   std::error_code writeAutoFDOData(StringRef OutputFilename);

bolt/lib/Profile/DataAggregator.cpp

std::error_code DataAggregator::printLBRHeatMap() {
   if (opts::OutputFilename == "-")
     HM.printSectionHotness(opts::OutputFilename);
   else
     HM.printSectionHotness(opts::OutputFilename + "-section-hotness.csv");
 
   return std::error_code();
 }
 
-std::error_code DataAggregator::parseBranchEvents() {
-  outs() << "PERF2BOLT: parse branch events...\n";
-  NamedRegionTimer T("parseBranch", "Parsing branch events", TimerGroupName,
-                     TimerGroupDesc, opts::TimeAggregator);
-
-  uint64_t NumTotalSamples = 0;
-  uint64_t NumEntries = 0;
-  uint64_t NumSamples = 0;
-  uint64_t NumSamplesNoLBR = 0;
-  uint64_t NumTraces = 0;
-  bool NeedsSkylakeFix = false;
-
-  while (hasData() && NumTotalSamples < opts::MaxSamples) {
-    ++NumTotalSamples;
-
-    ErrorOr<PerfBranchSample> SampleRes = parseBranchSample();
-    if (std::error_code EC = SampleRes.getError()) {
-      if (EC == errc::no_such_process)
-        continue;
-      return EC;
-    }
-    ++NumSamples;
-
-    PerfBranchSample &Sample = SampleRes.get();
-    if (opts::WriteAutoFDOData)
-      ++BasicSamples[Sample.PC];
-
-    if (Sample.LBR.empty()) {
-      ++NumSamplesNoLBR;
-      continue;
-    }
-
-    NumEntries += Sample.LBR.size();
-    if (BAT && Sample.LBR.size() == 32 && !NeedsSkylakeFix) {
-      errs() << "PERF2BOLT-WARNING: using Intel Skylake bug workaround\n";
-      NeedsSkylakeFix = true;
-    }
-
-    // LBRs are stored in reverse execution order. NextPC refers to the next
-    // recorded executed PC.
-    uint64_t NextPC = opts::UseEventPC ? Sample.PC : 0;
-    uint32_t NumEntry = 0;
-    for (const LBREntry &LBR : Sample.LBR) {
-      ++NumEntry;
-      // Hardware bug workaround: Intel Skylake (which has 32 LBR entries)
-      // sometimes record entry 32 as an exact copy of entry 31. This will cause
-      // us to likely record an invalid trace and generate a stale function for
-      // BAT mode (non BAT disassembles the function and is able to ignore this
-      // trace at aggregation time). Drop first 2 entries (last two, in
-      // chronological order)
-      if (NeedsSkylakeFix && NumEntry <= 2)
-        continue;
-      if (NextPC) {
-        // Record fall-through trace.
-        const uint64_t TraceFrom = LBR.To;
-        const uint64_t TraceTo = NextPC;
-        const BinaryFunction *TraceBF =
-            getBinaryFunctionContainingAddress(TraceFrom);
-        if (TraceBF && TraceBF->containsAddress(TraceTo)) {
-          FTInfo &Info = FallthroughLBRs[Trace(TraceFrom, TraceTo)];
-          if (TraceBF->containsAddress(LBR.From))
-            ++Info.InternCount;
-          else
-            ++Info.ExternCount;
-        } else {
-          if (TraceBF && getBinaryFunctionContainingAddress(TraceTo)) {
-            LLVM_DEBUG(dbgs()
-                       << "Invalid trace starting in "
-                       << TraceBF->getPrintName() << " @ "
-                       << Twine::utohexstr(TraceFrom - TraceBF->getAddress())
-                       << " and ending @ " << Twine::utohexstr(TraceTo)
-                       << '\n');
-            ++NumInvalidTraces;
-          } else {
-            LLVM_DEBUG(dbgs()
-                       << "Out of range trace starting in "
-                       << (TraceBF ? TraceBF->getPrintName() : "None") << " @ "
-                       << Twine::utohexstr(
+uint64_t DataAggregator::parseLBRSample(const PerfBranchSample &Sample,
+                                        bool NeedsSkylakeFix) {
+  uint64_t NumTraces{0};
+        const BinaryFunction *ToFunc =
+            getBinaryFunctionContainingAddress(TraceTo);
+        if (TraceBF && ToFunc) {
+          LLVM_DEBUG({
+            dbgs() << "Invalid trace starting in " << TraceBF->getPrintName()
+                   << formatv(" @ {0:x}", TraceFrom - TraceBF->getAddress())
+                   << formatv(" and ending @ {0:x}\n", TraceTo);
+          });
+          LLVM_DEBUG({
+            dbgs() << "Out of range trace starting in "
+                   << (TraceBF ? TraceBF->getPrintName() : "None")
+                   << formatv(" @ {0:x}",
                               TraceFrom - (TraceBF ? TraceBF->getAddress() : 0))
-                       << " and ending in "
-                       << (getBinaryFunctionContainingAddress(TraceTo)
-                               ? getBinaryFunctionContainingAddress(TraceTo)
-                                     ->getPrintName()
-                               : "None")
-                       << " @ "
-                       << Twine::utohexstr(
-                              TraceTo -
-                              (getBinaryFunctionContainingAddress(TraceTo)
-                                   ? getBinaryFunctionContainingAddress(TraceTo)
-                                         ->getAddress()
-                                   : 0))
-                       << '\n');
-            ++NumLongRangeTraces;
-          }
-        }
-        ++NumTraces;
-      }
-      NextPC = LBR.From;
+                   << (ToFunc ? ToFunc->getPrintName() : "None")
+                   << formatv(" @ {0:x}\n",
+                              TraceTo - (ToFunc ? ToFunc->getAddress() : 0));
+          });
 
-      uint64_t From = LBR.From;
-      if (!getBinaryFunctionContainingAddress(From))
-        From = 0;
-      uint64_t To = LBR.To;
-      if (!getBinaryFunctionContainingAddress(To))
-        To = 0;
-      if (!From && !To)
-        continue;
-      BranchInfo &Info = BranchLBRs[Trace(From, To)];
-      ++Info.TakenCount;
-      Info.MispredCount += LBR.Mispred;
-    }
+    uint64_t From = getBinaryFunctionContainingAddress(LBR.From) ? LBR.From : 0;
+    uint64_t To = getBinaryFunctionContainingAddress(LBR.To) ? LBR.To : 0;
+  return NumTraces;
+}
+
+std::error_code DataAggregator::parseBranchEvents() {
+  outs() << "PERF2BOLT: parse branch events...\n";
+  NamedRegionTimer T("parseBranch", "Parsing branch events", TimerGroupName,
+                     TimerGroupDesc, opts::TimeAggregator);
+
+  uint64_t NumTotalSamples = 0;
+  uint64_t NumEntries = 0;
+  uint64_t NumSamples = 0;
+  uint64_t NumSamplesNoLBR = 0;
+  uint64_t NumTraces = 0;
+  bool NeedsSkylakeFix = false;
+
+  while (hasData() && NumTotalSamples < opts::MaxSamples) {
+    ++NumTotalSamples;
+
+    ErrorOr<PerfBranchSample> SampleRes = parseBranchSample();
+    if (std::error_code EC = SampleRes.getError()) {
+      if (EC == errc::no_such_process)
+        continue;
+      return EC;
+    }
+    ++NumSamples;
+
+    PerfBranchSample &Sample = SampleRes.get();
+    if (opts::WriteAutoFDOData)
+      ++BasicSamples[Sample.PC];
+
+    if (Sample.LBR.empty()) {
+      ++NumSamplesNoLBR;
+      continue;
+    }
+
+    NumEntries += Sample.LBR.size();
+    if (BAT && Sample.LBR.size() == 32 && !NeedsSkylakeFix) {
+      errs() << "PERF2BOLT-WARNING: using Intel Skylake bug workaround\n";
+      NeedsSkylakeFix = true;
+    }
+
+    NumTraces += parseLBRSample(Sample, NeedsSkylakeFix);
   }
 
   for (const auto &LBR : BranchLBRs) {
     const Trace &Trace = LBR.first;
     if (BinaryFunction *BF = getBinaryFunctionContainingAddress(Trace.From))
       BF->setHasProfileAvailable();
     if (BinaryFunction *BF = getBinaryFunctionContainingAddress(Trace.To))
       BF->setHasProfileAvailable();