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diff --git a/lib/CodeGen/CodeGenPGO.h b/lib/CodeGen/CodeGenPGO.h
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+++ b/lib/CodeGen/CodeGenPGO.h
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+//===--- CodeGenPGO.h - PGO Instrumentation for LLVM CodeGen ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Instrumentation-based profile-guided optimization
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CLANG_CODEGEN_CODEGENPGO_H
+#define CLANG_CODEGEN_CODEGENPGO_H
+
+#include "CGBuilder.h"
+#include "CodeGenModule.h"
+#include "CodeGenTypes.h"
+#include "clang/Frontend/CodeGenOptions.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include <memory>
+
+namespace clang {
+namespace CodeGen {
+class RegionCounter;
+
+/// Per-function PGO state. This class should generally not be used directly,
+/// but instead through the CodeGenFunction and RegionCounter types.
+class CodeGenPGO {
+private:
+  CodeGenModule &CGM;
+  std::unique_ptr<std::string> PrefixedFuncName;
+  StringRef RawFuncName;
+  llvm::GlobalValue::LinkageTypes VarLinkage;
+
+  unsigned NumRegionCounters;
+  uint64_t FunctionHash;
+  llvm::GlobalVariable *RegionCounters;
+  std::unique_ptr<llvm::DenseMap<const Stmt *, unsigned>> RegionCounterMap;
+  std::unique_ptr<llvm::DenseMap<const Stmt *, uint64_t>> StmtCountMap;
+  std::unique_ptr<std::vector<uint64_t>> RegionCounts;
+  uint64_t CurrentRegionCount;
+
+public:
+  CodeGenPGO(CodeGenModule &CGM)
+      : CGM(CGM), NumRegionCounters(0), FunctionHash(0),
+        RegionCounters(nullptr), CurrentRegionCount(0) {}
+
+  /// Whether or not we have PGO region data for the current function. This is
+  /// false both when we have no data at all and when our data has been
+  /// discarded.
+  bool haveRegionCounts() const { return RegionCounts != nullptr; }
+
+  /// Get the string used to identify this function in the profile data.
+  /// For functions with local linkage, this includes the main file name.
+  StringRef getFuncName() const { return StringRef(*PrefixedFuncName); }
+  std::string getFuncVarName(StringRef VarName) const {
+    return ("__llvm_profile_" + VarName + "_" + RawFuncName).str();
+  }
+
+  /// Return the counter value of the current region.
+  uint64_t getCurrentRegionCount() const { return CurrentRegionCount; }
+
+  /// Set the counter value for the current region. This is used to keep track
+  /// of changes to the most recent counter from control flow and non-local
+  /// exits.
+  void setCurrentRegionCount(uint64_t Count) { CurrentRegionCount = Count; }
+
+  /// Indicate that the current region is never reached, and thus should have a
+  /// counter value of zero. This is important so that subsequent regions can
+  /// correctly track their parent counts.
+  void setCurrentRegionUnreachable() { setCurrentRegionCount(0); }
+
+  /// Check if an execution count is known for a given statement. If so, return
+  /// true and put the value in Count; else return false.
+  bool getStmtCount(const Stmt *S, uint64_t &Count) {
+    if (!StmtCountMap)
+      return false;
+    llvm::DenseMap<const Stmt*, uint64_t>::const_iterator
+      I = StmtCountMap->find(S);
+    if (I == StmtCountMap->end())
+      return false;
+    Count = I->second;
+    return true;
+  }
+
+  /// If the execution count for the current statement is known, record that
+  /// as the current count.
+  void setCurrentStmt(const Stmt *S) {
+    uint64_t Count;
+    if (getStmtCount(S, Count))
+      setCurrentRegionCount(Count);
+  }
+
+  /// Calculate branch weights appropriate for PGO data
+  llvm::MDNode *createBranchWeights(uint64_t TrueCount, uint64_t FalseCount);
+  llvm::MDNode *createBranchWeights(ArrayRef<uint64_t> Weights);
+  llvm::MDNode *createLoopWeights(const Stmt *Cond, RegionCounter &Cnt);
+
+  /// Assign counters to regions and configure them for PGO of a given
+  /// function. Does nothing if instrumentation is not enabled and either
+  /// generates global variables or associates PGO data with each of the
+  /// counters depending on whether we are generating or using instrumentation.
+  void assignRegionCounters(const Decl *D, llvm::Function *Fn);
+  /// Emit static data structures for instrumentation data.
+  void emitInstrumentationData();
+  /// Clean up region counter state. Must be called if assignRegionCounters is
+  /// used.
+  void destroyRegionCounters();
+  /// Emit static initialization code, if any.
+  static llvm::Function *emitInitialization(CodeGenModule &CGM);
+
+private:
+  void setFuncName(llvm::Function *Fn);
+  void mapRegionCounters(const Decl *D);
+  void computeRegionCounts(const Decl *D);
+  void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader,
+                               llvm::Function *Fn);
+  void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader,
+                        bool IsInMainFile);
+  void emitCounterVariables();
+  llvm::GlobalVariable *buildDataVar();
+
+  /// Emit code to increment the counter at the given index
+  void emitCounterIncrement(CGBuilderTy &Builder, unsigned Counter);
+
+  /// Return the region counter for the given statement. This should only be
+  /// called on statements that have a dedicated counter.
+  unsigned getRegionCounter(const Stmt *S) {
+    if (!RegionCounterMap)
+      return 0;
+    return (*RegionCounterMap)[S];
+  }
+
+  /// Return the region count for the counter at the given index.
+  uint64_t getRegionCount(unsigned Counter) {
+    if (!haveRegionCounts())
+      return 0;
+    return (*RegionCounts)[Counter];
+  }
+
+  friend class RegionCounter;
+};
+
+/// A counter for a particular region. This is the primary interface through
+/// which clients manage PGO counters and their values.
+class RegionCounter {
+  CodeGenPGO *PGO;
+  unsigned Counter;
+  uint64_t Count;
+  uint64_t ParentCount;
+  uint64_t RegionCount;
+  int64_t Adjust;
+
+  RegionCounter(CodeGenPGO &PGO, unsigned CounterIndex)
+    : PGO(&PGO), Counter(CounterIndex), Count(PGO.getRegionCount(Counter)),
+      ParentCount(PGO.getCurrentRegionCount()), Adjust(0) {}
+
+public:
+  RegionCounter(CodeGenPGO &PGO, const Stmt *S)
+    : PGO(&PGO), Counter(PGO.getRegionCounter(S)),
+      Count(PGO.getRegionCount(Counter)),
+      ParentCount(PGO.getCurrentRegionCount()), Adjust(0) {}
+
+  /// Get the value of the counter. In most cases this is the number of times
+  /// the region of the counter was entered, but for switch labels it's the
+  /// number of direct jumps to that label.
+  uint64_t getCount() const { return Count; }
+
+  /// Get the value of the counter with adjustments applied. Adjustments occur
+  /// when control enters or leaves the region abnormally; i.e., if there is a
+  /// jump to a label within the region, or if the function can return from
+  /// within the region. The adjusted count, then, is the value of the counter
+  /// at the end of the region.
+  uint64_t getAdjustedCount() const {
+    return Count + Adjust;
+  }
+
+  /// Get the value of the counter in this region's parent, i.e., the region
+  /// that was active when this region began. This is useful for deriving
+  /// counts in implicitly counted regions, like the false case of a condition
+  /// or the normal exits of a loop.
+  uint64_t getParentCount() const { return ParentCount; }
+
+  /// Activate the counter by emitting an increment and starting to track
+  /// adjustments. If AddIncomingFallThrough is true, the current region count
+  /// will be added to the counter for the purposes of tracking the region.
+  void beginRegion(CGBuilderTy &Builder, bool AddIncomingFallThrough=false) {
+    beginRegion(AddIncomingFallThrough);
+    PGO->emitCounterIncrement(Builder, Counter);
+  }
+  void beginRegion(bool AddIncomingFallThrough=false) {
+    RegionCount = Count;
+    if (AddIncomingFallThrough)
+      RegionCount += PGO->getCurrentRegionCount();
+    PGO->setCurrentRegionCount(RegionCount);
+  }
+
+  /// For counters on boolean branches, begins tracking adjustments for the
+  /// uncounted path.
+  void beginElseRegion() {
+    RegionCount = ParentCount - Count;
+    PGO->setCurrentRegionCount(RegionCount);
+  }
+
+  /// Reset the current region count.
+  void setCurrentRegionCount(uint64_t CurrentCount) {
+    RegionCount = CurrentCount;
+    PGO->setCurrentRegionCount(RegionCount);
+  }
+
+  /// Adjust for non-local control flow after emitting a subexpression or
+  /// substatement. This must be called to account for constructs such as gotos,
+  /// labels, and returns, so that we can ensure that our region's count is
+  /// correct in the code that follows.
+  void adjustForControlFlow() {
+    Adjust += PGO->getCurrentRegionCount() - RegionCount;
+    // Reset the region count in case this is called again later.
+    RegionCount = PGO->getCurrentRegionCount();
+  }
+
+  /// Commit all adjustments to the current region. If the region is a loop,
+  /// the LoopAdjust value should be the count of all the breaks and continues
+  /// from the loop, to compensate for those counts being deducted from the
+  /// adjustments for the body of the loop.
+  void applyAdjustmentsToRegion(uint64_t LoopAdjust) {
+    PGO->setCurrentRegionCount(ParentCount + Adjust + LoopAdjust);
+  }
+};
+
+}  // end namespace CodeGen
+}  // end namespace clang
+
+#endif