[llvm] [BOLT] Extend profile stats pass (PR #96969)

via llvm-commits llvm-commits at lists.llvm.org
Thu Jun 27 14:42:38 PDT 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-bolt

Author: ShatianWang (ShatianWang)

<details>
<summary>Changes</summary>

The original profile stats pass in BOLT reports profile a bias score together with a standard deviation for the entire profile. We added a flag `print-bucketed-profile-stats` that when used together with the original flag `print-profile-stats` will print additional profile quality metrics evaluating the profile against three characteristics that a perfect profile would have.

---

Patch is 38.71 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/96969.diff


4 Files Affected:

- (added) bolt/include/bolt/Passes/ProfileStats.h (+33) 
- (modified) bolt/lib/Passes/BinaryPasses.cpp (+2-90) 
- (modified) bolt/lib/Passes/CMakeLists.txt (+1) 
- (added) bolt/lib/Passes/ProfileStats.cpp (+817) 


``````````diff
diff --git a/bolt/include/bolt/Passes/ProfileStats.h b/bolt/include/bolt/Passes/ProfileStats.h
new file mode 100644
index 0000000000000..1f22603141bcc
--- /dev/null
+++ b/bolt/include/bolt/Passes/ProfileStats.h
@@ -0,0 +1,33 @@
+//===- bolt/Passes/ProfileStats.h - profile quality metrics ---*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Functions to print profile stats to quantify profile quality.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef BOLT_PASSES_PROFILESTATS_H
+#define BOLT_PASSES_PROFILESTATS_H
+
+#include <vector>
+
+namespace llvm {
+
+class raw_ostream;
+
+namespace bolt {
+class BinaryContext;
+namespace ProfileStats {
+
+/// Calculate and print various metrics related to profile quality
+void printAll(raw_ostream &OS, BinaryContext &BC);
+
+} // namespace ProfileStats
+} // namespace bolt
+} // namespace llvm
+
+#endif // BOLT_PASSES_PROFILESTATS_H
diff --git a/bolt/lib/Passes/BinaryPasses.cpp b/bolt/lib/Passes/BinaryPasses.cpp
index ecc2c08a30324..027e66b54f334 100644
--- a/bolt/lib/Passes/BinaryPasses.cpp
+++ b/bolt/lib/Passes/BinaryPasses.cpp
@@ -13,6 +13,7 @@
 #include "bolt/Passes/BinaryPasses.h"
 #include "bolt/Core/FunctionLayout.h"
 #include "bolt/Core/ParallelUtilities.h"
+#include "bolt/Passes/ProfileStats.h"
 #include "bolt/Passes/ReorderAlgorithm.h"
 #include "bolt/Passes/ReorderFunctions.h"
 #include "llvm/Support/CommandLine.h"
@@ -1280,96 +1281,7 @@ Error AssignSections::runOnFunctions(BinaryContext &BC) {
 }
 
 Error PrintProfileStats::runOnFunctions(BinaryContext &BC) {
-  double FlowImbalanceMean = 0.0;
-  size_t NumBlocksConsidered = 0;
-  double WorstBias = 0.0;
-  const BinaryFunction *WorstBiasFunc = nullptr;
-
-  // For each function CFG, we fill an IncomingMap with the sum of the frequency
-  // of incoming edges for each BB. Likewise for each OutgoingMap and the sum
-  // of the frequency of outgoing edges.
-  using FlowMapTy = std::unordered_map<const BinaryBasicBlock *, uint64_t>;
-  std::unordered_map<const BinaryFunction *, FlowMapTy> TotalIncomingMaps;
-  std::unordered_map<const BinaryFunction *, FlowMapTy> TotalOutgoingMaps;
-
-  // Compute mean
-  for (const auto &BFI : BC.getBinaryFunctions()) {
-    const BinaryFunction &Function = BFI.second;
-    if (Function.empty() || !Function.isSimple())
-      continue;
-    FlowMapTy &IncomingMap = TotalIncomingMaps[&Function];
-    FlowMapTy &OutgoingMap = TotalOutgoingMaps[&Function];
-    for (const BinaryBasicBlock &BB : Function) {
-      uint64_t TotalOutgoing = 0ULL;
-      auto SuccBIIter = BB.branch_info_begin();
-      for (BinaryBasicBlock *Succ : BB.successors()) {
-        uint64_t Count = SuccBIIter->Count;
-        if (Count == BinaryBasicBlock::COUNT_NO_PROFILE || Count == 0) {
-          ++SuccBIIter;
-          continue;
-        }
-        TotalOutgoing += Count;
-        IncomingMap[Succ] += Count;
-        ++SuccBIIter;
-      }
-      OutgoingMap[&BB] = TotalOutgoing;
-    }
-
-    size_t NumBlocks = 0;
-    double Mean = 0.0;
-    for (const BinaryBasicBlock &BB : Function) {
-      // Do not compute score for low frequency blocks, entry or exit blocks
-      if (IncomingMap[&BB] < 100 || OutgoingMap[&BB] == 0 || BB.isEntryPoint())
-        continue;
-      ++NumBlocks;
-      const double Difference = (double)OutgoingMap[&BB] - IncomingMap[&BB];
-      Mean += fabs(Difference / IncomingMap[&BB]);
-    }
-
-    FlowImbalanceMean += Mean;
-    NumBlocksConsidered += NumBlocks;
-    if (!NumBlocks)
-      continue;
-    double FuncMean = Mean / NumBlocks;
-    if (FuncMean > WorstBias) {
-      WorstBias = FuncMean;
-      WorstBiasFunc = &Function;
-    }
-  }
-  if (NumBlocksConsidered > 0)
-    FlowImbalanceMean /= NumBlocksConsidered;
-
-  // Compute standard deviation
-  NumBlocksConsidered = 0;
-  double FlowImbalanceVar = 0.0;
-  for (const auto &BFI : BC.getBinaryFunctions()) {
-    const BinaryFunction &Function = BFI.second;
-    if (Function.empty() || !Function.isSimple())
-      continue;
-    FlowMapTy &IncomingMap = TotalIncomingMaps[&Function];
-    FlowMapTy &OutgoingMap = TotalOutgoingMaps[&Function];
-    for (const BinaryBasicBlock &BB : Function) {
-      if (IncomingMap[&BB] < 100 || OutgoingMap[&BB] == 0)
-        continue;
-      ++NumBlocksConsidered;
-      const double Difference = (double)OutgoingMap[&BB] - IncomingMap[&BB];
-      FlowImbalanceVar +=
-          pow(fabs(Difference / IncomingMap[&BB]) - FlowImbalanceMean, 2);
-    }
-  }
-  if (NumBlocksConsidered) {
-    FlowImbalanceVar /= NumBlocksConsidered;
-    FlowImbalanceVar = sqrt(FlowImbalanceVar);
-  }
-
-  // Report to user
-  BC.outs() << format("BOLT-INFO: Profile bias score: %.4lf%% StDev: %.4lf%%\n",
-                      (100.0 * FlowImbalanceMean), (100.0 * FlowImbalanceVar));
-  if (WorstBiasFunc && opts::Verbosity >= 1) {
-    BC.outs() << "Worst average bias observed in "
-              << WorstBiasFunc->getPrintName() << "\n";
-    LLVM_DEBUG(WorstBiasFunc->dump());
-  }
+  ProfileStats::printAll(BC.outs(), BC);
   return Error::success();
 }
 
diff --git a/bolt/lib/Passes/CMakeLists.txt b/bolt/lib/Passes/CMakeLists.txt
index 04057a895d666..87e3c5498f284 100644
--- a/bolt/lib/Passes/CMakeLists.txt
+++ b/bolt/lib/Passes/CMakeLists.txt
@@ -29,6 +29,7 @@ add_llvm_library(LLVMBOLTPasses
   PatchEntries.cpp
   PettisAndHansen.cpp
   PLTCall.cpp
+  ProfileStats.cpp
   RegAnalysis.cpp
   RegReAssign.cpp
   ReorderAlgorithm.cpp
diff --git a/bolt/lib/Passes/ProfileStats.cpp b/bolt/lib/Passes/ProfileStats.cpp
new file mode 100644
index 0000000000000..cab9215b9462b
--- /dev/null
+++ b/bolt/lib/Passes/ProfileStats.cpp
@@ -0,0 +1,817 @@
+//===- bolt/Passes/ProfileStats.cpp - profile quality metrics ---*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Functions to print profile stats to quantify profile quality.
+//
+//===----------------------------------------------------------------------===//
+
+#include "bolt/Passes/ProfileStats.h"
+#include "bolt/Core/BinaryBasicBlock.h"
+#include "bolt/Core/BinaryFunction.h"
+#include "bolt/Utils/CommandLineOpts.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/raw_ostream.h"
+#include <queue>
+#include <unordered_map>
+#include <unordered_set>
+
+#define DEBUG_TYPE "bolt-opts"
+
+using namespace llvm;
+using namespace bolt;
+
+namespace opts {
+extern cl::opt<unsigned> Verbosity;
+cl::opt<bool> PrintBucketedMetrics(
+    "print-bucketed-profile-stats",
+    cl::desc("print profile quality stats for buckets of functions created "
+             "based on their execution counts."),
+    cl::Hidden, cl::cat(BoltCategory));
+cl::opt<unsigned>
+    NumFunctionsPerBucket("num-functions-per-bucket",
+                          cl::desc("Maximum number of functions per bucket."),
+                          cl::init(500), cl::ZeroOrMore, cl::Hidden,
+                          cl::cat(BoltOptCategory));
+cl::opt<unsigned> NumTopFunctions(
+    "num-top-functions",
+    cl::desc(
+        "Number of hottest functions to print aggregated profile stats of."),
+    cl::init(1000), cl::ZeroOrMore, cl::Hidden, cl::cat(BoltOptCategory));
+cl::opt<unsigned>
+    BBECThreshold("bbec-threshold",
+                  cl::desc("Minimum execution count of a basic block for it to "
+                           "be considered for profile stats computation."),
+                  cl::init(100), cl::ZeroOrMore, cl::Hidden,
+                  cl::cat(BoltOptCategory));
+} // namespace opts
+
+namespace {
+void printProfileBiasScore(raw_ostream &OS, BinaryContext &BC) {
+  double FlowImbalanceMean = 0.0;
+  size_t NumBlocksConsidered = 0;
+  double WorstBias = 0.0;
+  const BinaryFunction *WorstBiasFunc = nullptr;
+
+  // For each function CFG, we fill an IncomingMap with the sum of the frequency
+  // of incoming edges for each BB. Likewise for each OutgoingMap and the sum
+  // of the frequency of outgoing edges.
+  using FlowMapTy = std::unordered_map<const BinaryBasicBlock *, uint64_t>;
+  std::unordered_map<const BinaryFunction *, FlowMapTy> TotalIncomingMaps;
+  std::unordered_map<const BinaryFunction *, FlowMapTy> TotalOutgoingMaps;
+
+  // Compute mean
+  for (const auto &BFI : BC.getBinaryFunctions()) {
+    const BinaryFunction &Function = BFI.second;
+    if (Function.empty() || !Function.isSimple())
+      continue;
+    FlowMapTy &IncomingMap = TotalIncomingMaps[&Function];
+    FlowMapTy &OutgoingMap = TotalOutgoingMaps[&Function];
+    for (const BinaryBasicBlock &BB : Function) {
+      uint64_t TotalOutgoing = 0ULL;
+      auto SuccBIIter = BB.branch_info_begin();
+      for (BinaryBasicBlock *Succ : BB.successors()) {
+        uint64_t Count = SuccBIIter->Count;
+        if (Count == BinaryBasicBlock::COUNT_NO_PROFILE || Count == 0) {
+          ++SuccBIIter;
+          continue;
+        }
+        TotalOutgoing += Count;
+        IncomingMap[Succ] += Count;
+        ++SuccBIIter;
+      }
+      OutgoingMap[&BB] = TotalOutgoing;
+    }
+
+    size_t NumBlocks = 0;
+    double Mean = 0.0;
+    for (const BinaryBasicBlock &BB : Function) {
+      // Do not compute score for low frequency blocks, entry or exit blocks
+      if (IncomingMap[&BB] < 100 || OutgoingMap[&BB] == 0 || BB.isEntryPoint())
+        continue;
+      ++NumBlocks;
+      const double Difference = (double)OutgoingMap[&BB] - IncomingMap[&BB];
+      Mean += fabs(Difference / IncomingMap[&BB]);
+    }
+
+    FlowImbalanceMean += Mean;
+    NumBlocksConsidered += NumBlocks;
+    if (!NumBlocks)
+      continue;
+    double FuncMean = Mean / NumBlocks;
+    if (FuncMean > WorstBias) {
+      WorstBias = FuncMean;
+      WorstBiasFunc = &Function;
+    }
+  }
+  if (NumBlocksConsidered > 0)
+    FlowImbalanceMean /= NumBlocksConsidered;
+
+  // Compute standard deviation
+  NumBlocksConsidered = 0;
+  double FlowImbalanceVar = 0.0;
+  for (const auto &BFI : BC.getBinaryFunctions()) {
+    const BinaryFunction &Function = BFI.second;
+    if (Function.empty() || !Function.isSimple())
+      continue;
+    FlowMapTy &IncomingMap = TotalIncomingMaps[&Function];
+    FlowMapTy &OutgoingMap = TotalOutgoingMaps[&Function];
+    for (const BinaryBasicBlock &BB : Function) {
+      if (IncomingMap[&BB] < 100 || OutgoingMap[&BB] == 0)
+        continue;
+      ++NumBlocksConsidered;
+      const double Difference = (double)OutgoingMap[&BB] - IncomingMap[&BB];
+      FlowImbalanceVar +=
+          pow(fabs(Difference / IncomingMap[&BB]) - FlowImbalanceMean, 2);
+    }
+  }
+  if (NumBlocksConsidered) {
+    FlowImbalanceVar /= NumBlocksConsidered;
+    FlowImbalanceVar = sqrt(FlowImbalanceVar);
+  }
+
+  // Report to user
+  OS << format("BOLT-INFO: Profile bias score: %.4lf%% StDev: %.4lf%%\n",
+               (100.0 * FlowImbalanceMean), (100.0 * FlowImbalanceVar));
+  if (WorstBiasFunc && opts::Verbosity >= 1) {
+    OS << "Worst average bias observed in " << WorstBiasFunc->getPrintName()
+       << "\n";
+    LLVM_DEBUG(WorstBiasFunc->dump());
+  }
+}
+
+using FunctionListType = std::vector<const BinaryFunction *>;
+using function_iterator = FunctionListType::iterator;
+using FlowMapTy = std::unordered_map<const BinaryBasicBlock *, uint64_t>;
+using TotalFlowMapTy = std::unordered_map<const BinaryFunction *, FlowMapTy>;
+using FunctionFlowMapTy = std::unordered_map<const BinaryFunction *, uint64_t>;
+
+struct FlowInfo {
+  TotalFlowMapTy TotalIncomingMaps;
+  TotalFlowMapTy TotalOutgoingMaps;
+  TotalFlowMapTy TotalIECMaps;
+  TotalFlowMapTy TotalMaxCallMaps;
+  FunctionFlowMapTy CallGraphIncomingMap;
+};
+
+template <typename T>
+void printDistribution(raw_ostream &OS, std::vector<T> &values,
+                       bool Fraction = false) {
+  if (values.empty())
+    return;
+  // Sort values from largest to smallest and print the MAX, TOP 1%, 5%, 10%,
+  // 20%, 50%, 80%, MIN. If Fraction is true, then values are printed as
+  // fractions instead of integers.
+  std::sort(values.begin(), values.end());
+
+  auto printLine = [&](std::string Text, double Percent) {
+    int Rank = int(values.size() * (1.0 - Percent / 100));
+    if (Percent == 0)
+      Rank = values.size() - 1;
+    if (Fraction)
+      OS << "  " << Text << std::string(9 - Text.length(), ' ') << ": "
+         << format("%.2lf%%", values[Rank] * 100) << "\n";
+    else
+      OS << "  " << Text << std::string(9 - Text.length(), ' ') << ": "
+         << values[Rank] << "\n";
+  };
+
+  printLine("MAX", 0);
+  int percentages[] = {1, 5, 10, 20, 50, 80};
+  for (size_t i = 0; i < sizeof(percentages) / sizeof(percentages[0]); ++i) {
+    printLine("TOP " + std::to_string(percentages[i]) + "%", percentages[i]);
+  }
+  printLine("MIN", 100);
+}
+
+void printKECMetrics(raw_ostream &OS,
+                     iterator_range<function_iterator> &Functions,
+                     size_t BBECThreshold, FlowInfo &TotalFlowMap) {
+  // Each BB's Inferred Execution Count (IEC) equals to the max of its
+  // inflow, outflow, and individual call counts (if any).
+  // For each BB, its KEC = BinaryBasicBlock::getKnownExecutionCount() should be
+  // equal to its IEC in a perfect profile.
+  TotalFlowMapTy &TotalIECMaps = TotalFlowMap.TotalIECMaps;
+  size_t NumConsideredBBs = 0;
+  std::vector<size_t> PosDiffs;
+  for (auto it = Functions.begin(); it != Functions.end(); ++it) {
+    const BinaryFunction *Function = *it;
+    if (Function->size() <= 1)
+      continue;
+    FlowMapTy &IECMap = TotalIECMaps[Function];
+    for (const BinaryBasicBlock &BB : *Function) {
+      size_t IEC = IECMap[&BB];
+      size_t KEC = BB.getKnownExecutionCount();
+      size_t BBEC = std::max(IEC, KEC);
+      // Do not consider low frequency blocks.
+      // A low frequency block is a block whose max(IEC, KEC) is below a given
+      // threshold.
+      if (BBEC < BBECThreshold)
+        continue;
+      NumConsideredBBs++;
+      if (IEC <= KEC)
+        continue;
+      PosDiffs.push_back(IEC - KEC);
+    }
+  }
+  OS << "-------------------------------------------------------\n"
+     << "Metric 1: KEC <> IEC\n"
+     << "-------------------------------------------------------\n";
+  if (NumConsideredBBs == 0) {
+    OS << "  No BBs considered for this metric.\n";
+  } else {
+    OS << format("- %zu (%.2lf%%) of considered BBs have IEC > KEC\n",
+                 PosDiffs.size(),
+                 100.0 * (double)PosDiffs.size() / NumConsideredBBs);
+
+    if (!PosDiffs.empty()) {
+      OS << "- Distribution of (IEC - KEC) among considered BBs with IEC > "
+            "KEC\n";
+      printDistribution(OS, PosDiffs);
+    }
+  }
+}
+
+void printFlowConservationMetrics(raw_ostream &OS,
+                                  iterator_range<function_iterator> &Functions,
+                                  size_t BBECThreshold,
+                                  FlowInfo &TotalFlowMap) {
+  // Each non-entry non-exit BB should have its inflow equal to its outflow in a
+  // perfect profile.
+  TotalFlowMapTy &TotalIncomingMaps = TotalFlowMap.TotalIncomingMaps;
+  TotalFlowMapTy &TotalOutgoingMaps = TotalFlowMap.TotalOutgoingMaps;
+  TotalFlowMapTy &TotalIECMaps = TotalFlowMap.TotalIECMaps;
+
+  size_t NumConsideredBBs = 0;
+  size_t NumFocalBBs = 0;
+  std::vector<double> MaxDiffFracs;
+  std::vector<size_t> MaxDiffs;
+  for (auto it = Functions.begin(); it != Functions.end(); ++it) {
+    const BinaryFunction *Function = *it;
+    if (Function->size() <= 1)
+      continue;
+    FlowMapTy &IncomingMap = TotalIncomingMaps[Function];
+    FlowMapTy &OutgoingMap = TotalOutgoingMaps[Function];
+    FlowMapTy &IECMap = TotalIECMaps[Function];
+
+    size_t MaxDifference = 0.0;
+    double MaxDiffFrac = 0.0;
+    for (const BinaryBasicBlock &BB : *Function) {
+      size_t BBEC = std::max(IECMap[&BB], BB.getKnownExecutionCount());
+      // Do not consider low frequency blocks.
+      if (BBEC < BBECThreshold)
+        continue;
+      NumConsideredBBs++;
+      // Do not consider entry or exit blocks.
+      if (BB.succ_size() == 0 || BB.isEntryPoint())
+        continue;
+      NumFocalBBs++;
+
+      size_t LHS = IncomingMap[&BB];
+      size_t RHS = OutgoingMap[&BB];
+
+      size_t MIN = std::min(LHS, RHS);
+      size_t MAX = std::max(LHS, RHS);
+      const size_t Difference = MAX - MIN;
+      double DiffFrac = 0.0;
+      if (MAX > 0)
+        DiffFrac = (double)Difference / MAX;
+      if (DiffFrac > MaxDiffFrac)
+        MaxDiffFrac = DiffFrac;
+      if (Difference > MaxDifference)
+        MaxDifference = Difference;
+      if (opts::Verbosity >= 2 && DiffFrac > 0.5 && Difference > 500) {
+        OS << "Big flow conservation violation observed in " << BB.getName()
+           << " in function " << Function->getPrintName() << "\n";
+        LLVM_DEBUG(Function->dump());
+      }
+    }
+    if (NumFocalBBs > 0) {
+      MaxDiffFracs.push_back(MaxDiffFrac);
+      MaxDiffs.push_back(MaxDifference);
+    }
+  }
+
+  OS << "-------------------------------------------------------\n"
+     << "Metric 2: BB inflow <> BB outflow\n"
+     << "-------------------------------------------------------\n";
+  if (NumFocalBBs == 0) {
+    OS << "  No BBs considered for this metric.\n";
+  } else {
+    OS << format("Focus on %zu (%.2lf%%) of considered BBs that are neither "
+                 "function entries nor exits\n",
+                 NumFocalBBs, 100.0 * (double)NumFocalBBs / NumConsideredBBs)
+       << format("Focus on %zu (%.2lf%%) of considered functions that has at "
+                 "least 1 focal BBs\n",
+                 MaxDiffs.size(),
+                 100.0 * (double)MaxDiffs.size() /
+                     (std::distance(Functions.begin(), Functions.end())))
+       << "LHS = BB SUM inflow; RHS = BB SUM outflow\n"
+       << "MAX = MAX(LHS, RHS); MIN = MIN(LHS, RHS)\n";
+
+    if (!MaxDiffFracs.empty()) {
+      OS << "- Distribution of Worst[(MAX - MIN) / MAX] among all considered "
+            "functions\n";
+      printDistribution(OS, MaxDiffFracs, /*Fraction*/ true);
+    }
+    if (!MaxDiffs.empty()) {
+      OS << "- Distribution of Worst[MAX - MIN] among all considered "
+            "functions\n";
+      printDistribution(OS, MaxDiffs);
+    }
+  }
+}
+
+void printFlowCallConservationMetrics(
+    raw_ostream &OS, iterator_range<function_iterator> &Functions,
+    size_t BBECThreshold, FlowInfo &TotalFlowMap) {
+  // Each non-entry non-exit BB that makes function call(s) should have its
+  // max(inflow, outflow) equal to its call count(s) in a perfect profile.
+  TotalFlowMapTy &TotalIncomingMaps = TotalFlowMap.TotalIncomingMaps;
+  TotalFlowMapTy &TotalOutgoingMaps = TotalFlowMap.TotalOutgoingMaps;
+  TotalFlowMapTy &TotalIECMaps = TotalFlowMap.TotalIECMaps;
+  TotalFlowMapTy &TotalMaxCallMaps = TotalFlowMap.TotalMaxCallMaps;
+
+  size_t NumConsideredBBs = 0;
+  size_t NumFocalBBs = 0;
+  std::vector<double> MaxDiffFracs;
+  std::vector<size_t> MaxDiffs;
+  for (auto it = Functions.begin(); it != Functions.end(); ++it) {
+    const BinaryFunction *Function = *it;
+    if (Function->size() <= 1)
+      continue;
+    FlowMapTy &IncomingMap = TotalIncomingMaps[Function];
+    FlowMapTy &OutgoingMap = TotalOutgoingMaps[Function];
+    FlowMapTy &IECMap = TotalIECMaps[Function];
+    FlowMapTy &MaxCallMap = TotalMaxCallMaps[Function];
+
+    size_t MaxDifference = 0.0;
+    double MaxDiffFrac = 0.0;
+    bool FunctionConsidered = false;
+    for (const BinaryBasicBlock &BB : *Function) {
+      size_t BBEC = std::max(IECMap[&BB], BB.getKnownExecutionCount());
+      // Do not consider low frequency blocks.
+      if (BBEC < BBECThreshold)
+        continue;
+      NumConsideredBBs++;
+      // Do not consider BBs that do not make function calls.
+      if (MaxCallMap.find(&BB) == MaxCallMap.end())
+        continue;
+      NumFocalBBs++;
+      FunctionConsidered = true;
+
+      size_t LHS = std::max(IncomingMap[&BB], OutgoingMap[&BB]);
+      size...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/96969


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