[BOLT][NFC] Extract DataAggregator::parseLBRSample

Reviewed By: #bolt, rafauler Differential Revision: https://reviews.llvm.org/D150986
againull · May 20, 2023 · 860543d · 860543d
1 parent b75d6a4
commit 860543d
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Showing 2 changed files with 72 additions and 73 deletions.
diff --git a/bolt/include/bolt/Profile/DataAggregator.h b/bolt/include/bolt/Profile/DataAggregator.h
@@ -324,6 +324,9 @@ class DataAggregator : public DataReader {
   /// 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();
 

diff --git a/bolt/lib/Profile/DataAggregator.cpp b/bolt/lib/Profile/DataAggregator.cpp
@@ -1374,6 +1374,74 @@ std::error_code DataAggregator::printLBRHeatMap() {
   return std::error_code();
 }
 
+uint64_t DataAggregator::parseLBRSample(const PerfBranchSample &Sample,
+                                        bool NeedsSkylakeFix) {
+  uint64_t NumTraces{0};
+  // 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 {
+        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);
+          });
+          ++NumInvalidTraces;
+        } else {
+          LLVM_DEBUG({
+            dbgs() << "Out of range trace starting in "
+                   << (TraceBF ? TraceBF->getPrintName() : "None")
+                   << formatv(" @ {0:x}",
+                              TraceFrom - (TraceBF ? TraceBF->getAddress() : 0))
+                   << " and ending in "
+                   << (ToFunc ? ToFunc->getPrintName() : "None")
+                   << formatv(" @ {0:x}\n",
+                              TraceTo - (ToFunc ? ToFunc->getAddress() : 0));
+          });
+          ++NumLongRangeTraces;
+        }
+      }
+      ++NumTraces;
+    }
+    NextPC = LBR.From;
+
+    uint64_t From = getBinaryFunctionContainingAddress(LBR.From) ? LBR.From : 0;
+    uint64_t To = getBinaryFunctionContainingAddress(LBR.To) ? LBR.To : 0;
+    if (!From && !To)
+      continue;
+    BranchInfo &Info = BranchLBRs[Trace(From, To)];
+    ++Info.TakenCount;
+    Info.MispredCount += LBR.Mispred;
+  }
+  return NumTraces;
+}
+
 std::error_code DataAggregator::parseBranchEvents() {
   outs() << "PERF2BOLT: parse branch events...\n";
   NamedRegionTimer T("parseBranch", "Parsing branch events", TimerGroupName,
@@ -1412,79 +1480,7 @@ std::error_code DataAggregator::parseBranchEvents() {
       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(
-                              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;
-
-      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;
-    }
+    NumTraces += parseLBRSample(Sample, NeedsSkylakeFix);
   }
 
   for (const auto &LBR : BranchLBRs) {