xref: /llvm-project-15.0.7/llvm/lib/Transforms/IPO/SampleProfile.cpp (revision 85f025e5)

//===- SampleProfile.cpp - Incorporate sample profiles into the IR --------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the SampleProfileLoader transformation. This pass
// reads a profile file generated by a sampling profiler (e.g. Linux Perf -
// http://perf.wiki.kernel.org/) and generates IR metadata to reflect the
// profile information in the given profile.
//
// This pass generates branch weight annotations on the IR:
//
// - prof: Represents branch weights. This annotation is added to branches
//      to indicate the weights of each edge coming out of the branch.
//      The weight of each edge is the weight of the target block for
//      that edge. The weight of a block B is computed as the maximum
//      number of samples found in B.
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/IPO/SampleProfile.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/PriorityQueue.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Analysis/CallGraphSCCPass.h"
#include "llvm/Analysis/InlineAdvisor.h"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Analysis/ReplayInlineAdvisor.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/ValueSymbolTable.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/ProfileData/SampleProf.h"
#include "llvm/ProfileData/SampleProfReader.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/GenericDomTree.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/SampleContextTracker.h"
#include "llvm/Transforms/IPO/SampleProfileProbe.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Utils/CallPromotionUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <functional>
#include <limits>
#include <map>
#include <memory>
#include <queue>
#include <string>
#include <system_error>
#include <utility>
#include <vector>

using namespace llvm;
using namespace sampleprof;
using ProfileCount = Function::ProfileCount;
#define DEBUG_TYPE "sample-profile"
#define CSINLINE_DEBUG DEBUG_TYPE "-inline"

STATISTIC(NumCSInlined,
          "Number of functions inlined with context sensitive profile");
STATISTIC(NumCSNotInlined,
          "Number of functions not inlined with context sensitive profile");
STATISTIC(NumMismatchedProfile,
          "Number of functions with CFG mismatched profile");
STATISTIC(NumMatchedProfile, "Number of functions with CFG matched profile");
STATISTIC(NumDuplicatedInlinesite,
          "Number of inlined callsites with a partial distribution factor");

STATISTIC(NumCSInlinedHitMinLimit,
          "Number of functions with FDO inline stopped due to min size limit");
STATISTIC(NumCSInlinedHitMaxLimit,
          "Number of functions with FDO inline stopped due to max size limit");
STATISTIC(
    NumCSInlinedHitGrowthLimit,
    "Number of functions with FDO inline stopped due to growth size limit");

// Command line option to specify the file to read samples from. This is
// mainly used for debugging.
static cl::opt<std::string> SampleProfileFile(
    "sample-profile-file", cl::init(""), cl::value_desc("filename"),
    cl::desc("Profile file loaded by -sample-profile"), cl::Hidden);

// The named file contains a set of transformations that may have been applied
// to the symbol names between the program from which the sample data was
// collected and the current program's symbols.
static cl::opt<std::string> SampleProfileRemappingFile(
    "sample-profile-remapping-file", cl::init(""), cl::value_desc("filename"),
    cl::desc("Profile remapping file loaded by -sample-profile"), cl::Hidden);

static cl::opt<unsigned> SampleProfileMaxPropagateIterations(
    "sample-profile-max-propagate-iterations", cl::init(100),
    cl::desc("Maximum number of iterations to go through when propagating "
             "sample block/edge weights through the CFG."));

static cl::opt<unsigned> SampleProfileRecordCoverage(
    "sample-profile-check-record-coverage", cl::init(0), cl::value_desc("N"),
    cl::desc("Emit a warning if less than N% of records in the input profile "
             "are matched to the IR."));

static cl::opt<unsigned> SampleProfileSampleCoverage(
    "sample-profile-check-sample-coverage", cl::init(0), cl::value_desc("N"),
    cl::desc("Emit a warning if less than N% of samples in the input profile "
             "are matched to the IR."));

static cl::opt<bool> NoWarnSampleUnused(
    "no-warn-sample-unused", cl::init(false), cl::Hidden,
    cl::desc("Use this option to turn off/on warnings about function with "
             "samples but without debug information to use those samples. "));

static cl::opt<bool> ProfileSampleAccurate(
    "profile-sample-accurate", cl::Hidden, cl::init(false),
    cl::desc("If the sample profile is accurate, we will mark all un-sampled "
             "callsite and function as having 0 samples. Otherwise, treat "
             "un-sampled callsites and functions conservatively as unknown. "));

static cl::opt<bool> ProfileAccurateForSymsInList(
    "profile-accurate-for-symsinlist", cl::Hidden, cl::ZeroOrMore,
    cl::init(true),
    cl::desc("For symbols in profile symbol list, regard their profiles to "
             "be accurate. It may be overriden by profile-sample-accurate. "));

static cl::opt<bool> ProfileMergeInlinee(
    "sample-profile-merge-inlinee", cl::Hidden, cl::init(true),
    cl::desc("Merge past inlinee's profile to outline version if sample "
             "profile loader decided not to inline a call site. It will "
             "only be enabled when top-down order of profile loading is "
             "enabled. "));

static cl::opt<bool> ProfileTopDownLoad(
    "sample-profile-top-down-load", cl::Hidden, cl::init(true),
    cl::desc("Do profile annotation and inlining for functions in top-down "
             "order of call graph during sample profile loading. It only "
             "works for new pass manager. "));

static cl::opt<bool> UseProfileIndirectCallEdges(
    "use-profile-indirect-call-edges", cl::init(true), cl::Hidden,
    cl::desc("Considering indirect call samples from profile when top-down "
             "processing functions. Only CSSPGO is supported."));

static cl::opt<bool> UseProfileTopDownOrder(
    "use-profile-top-down-order", cl::init(false), cl::Hidden,
    cl::desc("Process functions in one SCC in a top-down order "
             "based on the input profile."));

static cl::opt<bool> ProfileSizeInline(
    "sample-profile-inline-size", cl::Hidden, cl::init(false),
    cl::desc("Inline cold call sites in profile loader if it's beneficial "
             "for code size."));

static cl::opt<int> ProfileInlineGrowthLimit(
    "sample-profile-inline-growth-limit", cl::Hidden, cl::init(12),
    cl::desc("The size growth ratio limit for proirity-based sample profile "
             "loader inlining."));

static cl::opt<int> ProfileInlineLimitMin(
    "sample-profile-inline-limit-min", cl::Hidden, cl::init(100),
    cl::desc("The lower bound of size growth limit for "
             "proirity-based sample profile loader inlining."));

static cl::opt<int> ProfileInlineLimitMax(
    "sample-profile-inline-limit-max", cl::Hidden, cl::init(10000),
    cl::desc("The upper bound of size growth limit for "
             "proirity-based sample profile loader inlining."));

static cl::opt<int> ProfileICPThreshold(
    "sample-profile-icp-threshold", cl::Hidden, cl::init(5),
    cl::desc(
        "Relative hotness threshold for indirect "
        "call promotion in proirity-based sample profile loader inlining."));

static cl::opt<int> SampleHotCallSiteThreshold(
    "sample-profile-hot-inline-threshold", cl::Hidden, cl::init(3000),
    cl::desc("Hot callsite threshold for proirity-based sample profile loader "
             "inlining."));

static cl::opt<bool> CallsitePrioritizedInline(
    "sample-profile-prioritized-inline", cl::Hidden, cl::ZeroOrMore,
    cl::init(false),
    cl::desc("Use call site prioritized inlining for sample profile loader."
             "Currently only CSSPGO is supported."));

static cl::opt<int> SampleColdCallSiteThreshold(
    "sample-profile-cold-inline-threshold", cl::Hidden, cl::init(45),
    cl::desc("Threshold for inlining cold callsites"));

static cl::opt<std::string> ProfileInlineReplayFile(
    "sample-profile-inline-replay", cl::init(""), cl::value_desc("filename"),
    cl::desc(
        "Optimization remarks file containing inline remarks to be replayed "
        "by inlining from sample profile loader."),
    cl::Hidden);

namespace {

using BlockWeightMap = DenseMap<const BasicBlock *, uint64_t>;
using EquivalenceClassMap = DenseMap<const BasicBlock *, const BasicBlock *>;
using Edge = std::pair<const BasicBlock *, const BasicBlock *>;
using EdgeWeightMap = DenseMap<Edge, uint64_t>;
using BlockEdgeMap =
    DenseMap<const BasicBlock *, SmallVector<const BasicBlock *, 8>>;

class SampleCoverageTracker {
public:
  bool markSamplesUsed(const FunctionSamples *FS, uint32_t LineOffset,
                       uint32_t Discriminator, uint64_t Samples);
  unsigned computeCoverage(unsigned Used, unsigned Total) const;
  unsigned countUsedRecords(const FunctionSamples *FS,
                            ProfileSummaryInfo *PSI) const;
  unsigned countBodyRecords(const FunctionSamples *FS,
                            ProfileSummaryInfo *PSI) const;
  uint64_t getTotalUsedSamples() const { return TotalUsedSamples; }
  uint64_t countBodySamples(const FunctionSamples *FS,
                            ProfileSummaryInfo *PSI) const;

  void clear() {
    SampleCoverage.clear();
    TotalUsedSamples = 0;
  }
  inline void setProfAccForSymsInList(bool V) { ProfAccForSymsInList = V; }

private:
  using BodySampleCoverageMap = std::map<LineLocation, unsigned>;
  using FunctionSamplesCoverageMap =
      DenseMap<const FunctionSamples *, BodySampleCoverageMap>;

  /// Coverage map for sampling records.
  ///
  /// This map keeps a record of sampling records that have been matched to
  /// an IR instruction. This is used to detect some form of staleness in
  /// profiles (see flag -sample-profile-check-coverage).
  ///
  /// Each entry in the map corresponds to a FunctionSamples instance.  This is
  /// another map that counts how many times the sample record at the
  /// given location has been used.
  FunctionSamplesCoverageMap SampleCoverage;

  /// Number of samples used from the profile.
  ///
  /// When a sampling record is used for the first time, the samples from
  /// that record are added to this accumulator.  Coverage is later computed
  /// based on the total number of samples available in this function and
  /// its callsites.
  ///
  /// Note that this accumulator tracks samples used from a single function
  /// and all the inlined callsites. Strictly, we should have a map of counters
  /// keyed by FunctionSamples pointers, but these stats are cleared after
  /// every function, so we just need to keep a single counter.
  uint64_t TotalUsedSamples = 0;

  // For symbol in profile symbol list, whether to regard their profiles
  // to be accurate. This is passed from the SampleLoader instance.
  bool ProfAccForSymsInList = false;
};

class GUIDToFuncNameMapper {
public:
  GUIDToFuncNameMapper(Module &M, SampleProfileReader &Reader,
                        DenseMap<uint64_t, StringRef> &GUIDToFuncNameMap)
      : CurrentReader(Reader), CurrentModule(M),
      CurrentGUIDToFuncNameMap(GUIDToFuncNameMap) {
    if (!CurrentReader.useMD5())
      return;

    for (const auto &F : CurrentModule) {
      StringRef OrigName = F.getName();
      CurrentGUIDToFuncNameMap.insert(
          {Function::getGUID(OrigName), OrigName});

      // Local to global var promotion used by optimization like thinlto
      // will rename the var and add suffix like ".llvm.xxx" to the
      // original local name. In sample profile, the suffixes of function
      // names are all stripped. Since it is possible that the mapper is
      // built in post-thin-link phase and var promotion has been done,
      // we need to add the substring of function name without the suffix
      // into the GUIDToFuncNameMap.
      StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
      if (CanonName != OrigName)
        CurrentGUIDToFuncNameMap.insert(
            {Function::getGUID(CanonName), CanonName});
    }

    // Update GUIDToFuncNameMap for each function including inlinees.
    SetGUIDToFuncNameMapForAll(&CurrentGUIDToFuncNameMap);
  }

  ~GUIDToFuncNameMapper() {
    if (!CurrentReader.useMD5())
      return;

    CurrentGUIDToFuncNameMap.clear();

    // Reset GUIDToFuncNameMap for of each function as they're no
    // longer valid at this point.
    SetGUIDToFuncNameMapForAll(nullptr);
  }

private:
  void SetGUIDToFuncNameMapForAll(DenseMap<uint64_t, StringRef> *Map) {
    std::queue<FunctionSamples *> FSToUpdate;
    for (auto &IFS : CurrentReader.getProfiles()) {
      FSToUpdate.push(&IFS.second);
    }

    while (!FSToUpdate.empty()) {
      FunctionSamples *FS = FSToUpdate.front();
      FSToUpdate.pop();
      FS->GUIDToFuncNameMap = Map;
      for (const auto &ICS : FS->getCallsiteSamples()) {
        const FunctionSamplesMap &FSMap = ICS.second;
        for (auto &IFS : FSMap) {
          FunctionSamples &FS = const_cast<FunctionSamples &>(IFS.second);
          FSToUpdate.push(&FS);
        }
      }
    }
  }

  SampleProfileReader &CurrentReader;
  Module &CurrentModule;
  DenseMap<uint64_t, StringRef> &CurrentGUIDToFuncNameMap;
};

// Inline candidate used by iterative callsite prioritized inliner
struct InlineCandidate {
  CallBase *CallInstr;
  const FunctionSamples *CalleeSamples;
  // Prorated callsite count, which will be used to guide inlining. For example,
  // if a callsite is duplicated in LTO prelink, then in LTO postlink the two
  // copies will get their own distribution factors and their prorated counts
  // will be used to decide if they should be inlined independently.
  uint64_t CallsiteCount;
  // Call site distribution factor to prorate the profile samples for a
  // duplicated callsite. Default value is 1.0.
  float CallsiteDistribution;
};

// Inline candidate comparer using call site weight
struct CandidateComparer {
  bool operator()(const InlineCandidate &LHS, const InlineCandidate &RHS) {
    if (LHS.CallsiteCount != RHS.CallsiteCount)
      return LHS.CallsiteCount < RHS.CallsiteCount;

    // Tie breaker using GUID so we have stable/deterministic inlining order
    assert(LHS.CalleeSamples && RHS.CalleeSamples &&
           "Expect non-null FunctionSamples");
    return LHS.CalleeSamples->getGUID(LHS.CalleeSamples->getName()) <
           RHS.CalleeSamples->getGUID(RHS.CalleeSamples->getName());
  }
};

using CandidateQueue =
    PriorityQueue<InlineCandidate, std::vector<InlineCandidate>,
                  CandidateComparer>;

class SampleProfileLoaderBaseImpl {
public:
  SampleProfileLoaderBaseImpl(std::string Name) : Filename(Name) {}
  void dump() { Reader->dump(); }

protected:
  friend class SampleCoverageTracker;

  ~SampleProfileLoaderBaseImpl() = default;

  unsigned getFunctionLoc(Function &F);
  virtual ErrorOr<uint64_t> getInstWeight(const Instruction &Inst);
  ErrorOr<uint64_t> getInstWeightImpl(const Instruction &Inst);
  ErrorOr<uint64_t> getBlockWeight(const BasicBlock *BB);
  mutable DenseMap<const DILocation *, const FunctionSamples *>
      DILocation2SampleMap;
  virtual const FunctionSamples *
  findFunctionSamples(const Instruction &I) const;
  void printEdgeWeight(raw_ostream &OS, Edge E);
  void printBlockWeight(raw_ostream &OS, const BasicBlock *BB) const;
  void printBlockEquivalence(raw_ostream &OS, const BasicBlock *BB);
  bool computeBlockWeights(Function &F);
  void findEquivalenceClasses(Function &F);
  template <bool IsPostDom>
  void findEquivalencesFor(BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
                           DominatorTreeBase<BasicBlock, IsPostDom> *DomTree);

  void propagateWeights(Function &F);
  uint64_t visitEdge(Edge E, unsigned *NumUnknownEdges, Edge *UnknownEdge);
  void buildEdges(Function &F);
  bool propagateThroughEdges(Function &F, bool UpdateBlockCount);
  void clearFunctionData();
  void computeDominanceAndLoopInfo(Function &F);
  bool
  computeAndPropagateWeights(Function &F,
                             const DenseSet<GlobalValue::GUID> &InlinedGUIDs);
  void emitCoverageRemarks(Function &F);

  /// Map basic blocks to their computed weights.
  ///
  /// The weight of a basic block is defined to be the maximum
  /// of all the instruction weights in that block.
  BlockWeightMap BlockWeights;

  /// Map edges to their computed weights.
  ///
  /// Edge weights are computed by propagating basic block weights in
  /// SampleProfile::propagateWeights.
  EdgeWeightMap EdgeWeights;

  /// Set of visited blocks during propagation.
  SmallPtrSet<const BasicBlock *, 32> VisitedBlocks;

  /// Set of visited edges during propagation.
  SmallSet<Edge, 32> VisitedEdges;

  /// Equivalence classes for block weights.
  ///
  /// Two blocks BB1 and BB2 are in the same equivalence class if they
  /// dominate and post-dominate each other, and they are in the same loop
  /// nest. When this happens, the two blocks are guaranteed to execute
  /// the same number of times.
  EquivalenceClassMap EquivalenceClass;

  /// Dominance, post-dominance and loop information.
  std::unique_ptr<DominatorTree> DT;
  std::unique_ptr<PostDominatorTree> PDT;
  std::unique_ptr<LoopInfo> LI;

  /// Predecessors for each basic block in the CFG.
  BlockEdgeMap Predecessors;

  /// Successors for each basic block in the CFG.
  BlockEdgeMap Successors;

  SampleCoverageTracker CoverageTracker;

  /// Profile reader object.
  std::unique_ptr<SampleProfileReader> Reader;

  /// Samples collected for the body of this function.
  FunctionSamples *Samples = nullptr;

  /// Name of the profile file to load.
  std::string Filename;

  /// Profile Summary Info computed from sample profile.
  ProfileSummaryInfo *PSI = nullptr;

  /// Optimization Remark Emitter used to emit diagnostic remarks.
  OptimizationRemarkEmitter *ORE = nullptr;
};

/// Sample profile pass.
///
/// This pass reads profile data from the file specified by
/// -sample-profile-file and annotates every affected function with the
/// profile information found in that file.
class SampleProfileLoader final : public SampleProfileLoaderBaseImpl {
public:
  SampleProfileLoader(
      StringRef Name, StringRef RemapName, ThinOrFullLTOPhase LTOPhase,
      std::function<AssumptionCache &(Function &)> GetAssumptionCache,
      std::function<TargetTransformInfo &(Function &)> GetTargetTransformInfo,
      std::function<const TargetLibraryInfo &(Function &)> GetTLI)
      : SampleProfileLoaderBaseImpl(std::string(Name)),
        GetAC(std::move(GetAssumptionCache)),
        GetTTI(std::move(GetTargetTransformInfo)), GetTLI(std::move(GetTLI)),
        RemappingFilename(std::string(RemapName)), LTOPhase(LTOPhase) {}

  bool doInitialization(Module &M, FunctionAnalysisManager *FAM = nullptr);
  bool runOnModule(Module &M, ModuleAnalysisManager *AM,
                   ProfileSummaryInfo *_PSI, CallGraph *CG);

protected:
  bool runOnFunction(Function &F, ModuleAnalysisManager *AM);
  bool emitAnnotations(Function &F);
  ErrorOr<uint64_t> getInstWeight(const Instruction &I) override;
  ErrorOr<uint64_t> getProbeWeight(const Instruction &I);
  const FunctionSamples *findCalleeFunctionSamples(const CallBase &I) const;
  const FunctionSamples *
  findFunctionSamples(const Instruction &I) const override;
  std::vector<const FunctionSamples *>
  findIndirectCallFunctionSamples(const Instruction &I, uint64_t &Sum) const;
  // Attempt to promote indirect call and also inline the promoted call
  bool tryPromoteAndInlineCandidate(
      Function &F, InlineCandidate &Candidate, uint64_t SumOrigin,
      uint64_t &Sum, DenseSet<Instruction *> &PromotedInsns,
      SmallVector<CallBase *, 8> *InlinedCallSites = nullptr);
  bool inlineHotFunctions(Function &F,
                          DenseSet<GlobalValue::GUID> &InlinedGUIDs);
  InlineCost shouldInlineCandidate(InlineCandidate &Candidate);
  bool getInlineCandidate(InlineCandidate *NewCandidate, CallBase *CB);
  bool
  tryInlineCandidate(InlineCandidate &Candidate,
                     SmallVector<CallBase *, 8> *InlinedCallSites = nullptr);
  bool
  inlineHotFunctionsWithPriority(Function &F,
                                 DenseSet<GlobalValue::GUID> &InlinedGUIDs);
  // Inline cold/small functions in addition to hot ones
  bool shouldInlineColdCallee(CallBase &CallInst);
  void emitOptimizationRemarksForInlineCandidates(
      const SmallVectorImpl<CallBase *> &Candidates, const Function &F,
      bool Hot);
  std::vector<Function *> buildFunctionOrder(Module &M, CallGraph *CG);
  void addCallGraphEdges(CallGraph &CG, const FunctionSamples &Samples);
  void replaceCallGraphEdges(CallGraph &CG, StringMap<Function *> &SymbolMap);
  void generateMDProfMetadata(Function &F);

  /// Map from function name to Function *. Used to find the function from
  /// the function name. If the function name contains suffix, additional
  /// entry is added to map from the stripped name to the function if there
  /// is one-to-one mapping.
  StringMap<Function *> SymbolMap;

  std::function<AssumptionCache &(Function &)> GetAC;
  std::function<TargetTransformInfo &(Function &)> GetTTI;
  std::function<const TargetLibraryInfo &(Function &)> GetTLI;

  /// Profile tracker for different context.
  std::unique_ptr<SampleContextTracker> ContextTracker;

  /// Name of the profile remapping file to load.
  std::string RemappingFilename;

  /// Flag indicating whether the profile input loaded successfully.
  bool ProfileIsValid = false;

  /// Flag indicating whether input profile is context-sensitive
  bool ProfileIsCS = false;

  /// Flag indicating which LTO/ThinLTO phase the pass is invoked in.
  ///
  /// We need to know the LTO phase because for example in ThinLTOPrelink
  /// phase, in annotation, we should not promote indirect calls. Instead,
  /// we will mark GUIDs that needs to be annotated to the function.
  ThinOrFullLTOPhase LTOPhase;

  /// Profle Symbol list tells whether a function name appears in the binary
  /// used to generate the current profile.
  std::unique_ptr<ProfileSymbolList> PSL;

  /// Total number of samples collected in this profile.
  ///
  /// This is the sum of all the samples collected in all the functions executed
  /// at runtime.
  uint64_t TotalCollectedSamples = 0;

  // Information recorded when we declined to inline a call site
  // because we have determined it is too cold is accumulated for
  // each callee function. Initially this is just the entry count.
  struct NotInlinedProfileInfo {
    uint64_t entryCount;
  };
  DenseMap<Function *, NotInlinedProfileInfo> notInlinedCallInfo;

  // GUIDToFuncNameMap saves the mapping from GUID to the symbol name, for
  // all the function symbols defined or declared in current module.
  DenseMap<uint64_t, StringRef> GUIDToFuncNameMap;

  // All the Names used in FunctionSamples including outline function
  // names, inline instance names and call target names.
  StringSet<> NamesInProfile;

  // For symbol in profile symbol list, whether to regard their profiles
  // to be accurate. It is mainly decided by existance of profile symbol
  // list and -profile-accurate-for-symsinlist flag, but it can be
  // overriden by -profile-sample-accurate or profile-sample-accurate
  // attribute.
  bool ProfAccForSymsInList;

  // External inline advisor used to replay inline decision from remarks.
  std::unique_ptr<ReplayInlineAdvisor> ExternalInlineAdvisor;

  // A pseudo probe helper to correlate the imported sample counts.
  std::unique_ptr<PseudoProbeManager> ProbeManager;
};

class SampleProfileLoaderLegacyPass : public ModulePass {
public:
  // Class identification, replacement for typeinfo
  static char ID;

  SampleProfileLoaderLegacyPass(
      StringRef Name = SampleProfileFile,
      ThinOrFullLTOPhase LTOPhase = ThinOrFullLTOPhase::None)
      : ModulePass(ID), SampleLoader(
                            Name, SampleProfileRemappingFile, LTOPhase,
                            [&](Function &F) -> AssumptionCache & {
                              return ACT->getAssumptionCache(F);
                            },
                            [&](Function &F) -> TargetTransformInfo & {
                              return TTIWP->getTTI(F);
                            },
                            [&](Function &F) -> TargetLibraryInfo & {
                              return TLIWP->getTLI(F);
                            }) {
    initializeSampleProfileLoaderLegacyPassPass(
        *PassRegistry::getPassRegistry());
  }

  void dump() { SampleLoader.dump(); }

  bool doInitialization(Module &M) override {
    return SampleLoader.doInitialization(M);
  }

  StringRef getPassName() const override { return "Sample profile pass"; }
  bool runOnModule(Module &M) override;

  void getAnalysisUsage(AnalysisUsage &AU) const override {
    AU.addRequired<AssumptionCacheTracker>();
    AU.addRequired<TargetTransformInfoWrapperPass>();
    AU.addRequired<TargetLibraryInfoWrapperPass>();
    AU.addRequired<ProfileSummaryInfoWrapperPass>();
  }

private:
  SampleProfileLoader SampleLoader;
  AssumptionCacheTracker *ACT = nullptr;
  TargetTransformInfoWrapperPass *TTIWP = nullptr;
  TargetLibraryInfoWrapperPass *TLIWP = nullptr;
};

} // end anonymous namespace

/// Return true if the given callsite is hot wrt to hot cutoff threshold.
///
/// Functions that were inlined in the original binary will be represented
/// in the inline stack in the sample profile. If the profile shows that
/// the original inline decision was "good" (i.e., the callsite is executed
/// frequently), then we will recreate the inline decision and apply the
/// profile from the inlined callsite.
///
/// To decide whether an inlined callsite is hot, we compare the callsite
/// sample count with the hot cutoff computed by ProfileSummaryInfo, it is
/// regarded as hot if the count is above the cutoff value.
///
/// When ProfileAccurateForSymsInList is enabled and profile symbol list
/// is present, functions in the profile symbol list but without profile will
/// be regarded as cold and much less inlining will happen in CGSCC inlining
/// pass, so we tend to lower the hot criteria here to allow more early
/// inlining to happen for warm callsites and it is helpful for performance.
static bool callsiteIsHot(const FunctionSamples *CallsiteFS,
                          ProfileSummaryInfo *PSI, bool ProfAccForSymsInList) {
  if (!CallsiteFS)
    return false; // The callsite was not inlined in the original binary.

  assert(PSI && "PSI is expected to be non null");
  uint64_t CallsiteTotalSamples = CallsiteFS->getTotalSamples();
  if (ProfAccForSymsInList)
    return !PSI->isColdCount(CallsiteTotalSamples);
  else
    return PSI->isHotCount(CallsiteTotalSamples);
}

/// Mark as used the sample record for the given function samples at
/// (LineOffset, Discriminator).
///
/// \returns true if this is the first time we mark the given record.
bool SampleCoverageTracker::markSamplesUsed(const FunctionSamples *FS,
                                            uint32_t LineOffset,
                                            uint32_t Discriminator,
                                            uint64_t Samples) {
  LineLocation Loc(LineOffset, Discriminator);
  unsigned &Count = SampleCoverage[FS][Loc];
  bool FirstTime = (++Count == 1);
  if (FirstTime)
    TotalUsedSamples += Samples;
  return FirstTime;
}

/// Return the number of sample records that were applied from this profile.
///
/// This count does not include records from cold inlined callsites.
unsigned
SampleCoverageTracker::countUsedRecords(const FunctionSamples *FS,
                                        ProfileSummaryInfo *PSI) const {
  auto I = SampleCoverage.find(FS);

  // The size of the coverage map for FS represents the number of records
  // that were marked used at least once.
  unsigned Count = (I != SampleCoverage.end()) ? I->second.size() : 0;

  // If there are inlined callsites in this function, count the samples found
  // in the respective bodies. However, do not bother counting callees with 0
  // total samples, these are callees that were never invoked at runtime.
  for (const auto &I : FS->getCallsiteSamples())
    for (const auto &J : I.second) {
      const FunctionSamples *CalleeSamples = &J.second;
      if (callsiteIsHot(CalleeSamples, PSI, ProfAccForSymsInList))
        Count += countUsedRecords(CalleeSamples, PSI);
    }

  return Count;
}

/// Return the number of sample records in the body of this profile.
///
/// This count does not include records from cold inlined callsites.
unsigned
SampleCoverageTracker::countBodyRecords(const FunctionSamples *FS,
                                        ProfileSummaryInfo *PSI) const {
  unsigned Count = FS->getBodySamples().size();

  // Only count records in hot callsites.
  for (const auto &I : FS->getCallsiteSamples())
    for (const auto &J : I.second) {
      const FunctionSamples *CalleeSamples = &J.second;
      if (callsiteIsHot(CalleeSamples, PSI, ProfAccForSymsInList))
        Count += countBodyRecords(CalleeSamples, PSI);
    }

  return Count;
}

/// Return the number of samples collected in the body of this profile.
///
/// This count does not include samples from cold inlined callsites.
uint64_t
SampleCoverageTracker::countBodySamples(const FunctionSamples *FS,
                                        ProfileSummaryInfo *PSI) const {
  uint64_t Total = 0;
  for (const auto &I : FS->getBodySamples())
    Total += I.second.getSamples();

  // Only count samples in hot callsites.
  for (const auto &I : FS->getCallsiteSamples())
    for (const auto &J : I.second) {
      const FunctionSamples *CalleeSamples = &J.second;
      if (callsiteIsHot(CalleeSamples, PSI, ProfAccForSymsInList))
        Total += countBodySamples(CalleeSamples, PSI);
    }

  return Total;
}

/// Return the fraction of sample records used in this profile.
///
/// The returned value is an unsigned integer in the range 0-100 indicating
/// the percentage of sample records that were used while applying this
/// profile to the associated function.
unsigned SampleCoverageTracker::computeCoverage(unsigned Used,
                                                unsigned Total) const {
  assert(Used <= Total &&
         "number of used records cannot exceed the total number of records");
  return Total > 0 ? Used * 100 / Total : 100;
}

/// Clear all the per-function data used to load samples and propagate weights.
void SampleProfileLoaderBaseImpl::clearFunctionData() {
  BlockWeights.clear();
  EdgeWeights.clear();
  VisitedBlocks.clear();
  VisitedEdges.clear();
  EquivalenceClass.clear();
  DT = nullptr;
  PDT = nullptr;
  LI = nullptr;
  Predecessors.clear();
  Successors.clear();
  CoverageTracker.clear();
}

#ifndef NDEBUG
/// Print the weight of edge \p E on stream \p OS.
///
/// \param OS  Stream to emit the output to.
/// \param E  Edge to print.
void SampleProfileLoaderBaseImpl::printEdgeWeight(raw_ostream &OS, Edge E) {
  OS << "weight[" << E.first->getName() << "->" << E.second->getName()
     << "]: " << EdgeWeights[E] << "\n";
}

/// Print the equivalence class of block \p BB on stream \p OS.
///
/// \param OS  Stream to emit the output to.
/// \param BB  Block to print.
void SampleProfileLoaderBaseImpl::printBlockEquivalence(raw_ostream &OS,
                                                        const BasicBlock *BB) {
  const BasicBlock *Equiv = EquivalenceClass[BB];
  OS << "equivalence[" << BB->getName()
     << "]: " << ((Equiv) ? EquivalenceClass[BB]->getName() : "NONE") << "\n";
}

/// Print the weight of block \p BB on stream \p OS.
///
/// \param OS  Stream to emit the output to.
/// \param BB  Block to print.
void SampleProfileLoaderBaseImpl::printBlockWeight(raw_ostream &OS,
                                                   const BasicBlock *BB) const {
  const auto &I = BlockWeights.find(BB);
  uint64_t W = (I == BlockWeights.end() ? 0 : I->second);
  OS << "weight[" << BB->getName() << "]: " << W << "\n";
}
#endif

/// Get the weight for an instruction.
///
/// The "weight" of an instruction \p Inst is the number of samples
/// collected on that instruction at runtime. To retrieve it, we
/// need to compute the line number of \p Inst relative to the start of its
/// function. We use HeaderLineno to compute the offset. We then
/// look up the samples collected for \p Inst using BodySamples.
///
/// \param Inst Instruction to query.
///
/// \returns the weight of \p Inst.
ErrorOr<uint64_t>
SampleProfileLoaderBaseImpl::getInstWeight(const Instruction &Inst) {
  return getInstWeightImpl(Inst);
}

ErrorOr<uint64_t> SampleProfileLoader::getInstWeight(const Instruction &Inst) {
  if (FunctionSamples::ProfileIsProbeBased)
    return getProbeWeight(Inst);

  const DebugLoc &DLoc = Inst.getDebugLoc();
  if (!DLoc)
    return std::error_code();

  // Ignore all intrinsics, phinodes and branch instructions.
  // Branch and phinodes instruction usually contains debug info from sources
  // outside of the residing basic block, thus we ignore them during annotation.
  if (isa<BranchInst>(Inst) || isa<IntrinsicInst>(Inst) || isa<PHINode>(Inst))
    return std::error_code();

  // If a direct call/invoke instruction is inlined in profile
  // (findCalleeFunctionSamples returns non-empty result), but not inlined here,
  // it means that the inlined callsite has no sample, thus the call
  // instruction should have 0 count.
  if (!ProfileIsCS)
    if (const auto *CB = dyn_cast<CallBase>(&Inst))
      if (!CB->isIndirectCall() && findCalleeFunctionSamples(*CB))
        return 0;

  return getInstWeightImpl(Inst);
}

ErrorOr<uint64_t>
SampleProfileLoaderBaseImpl::getInstWeightImpl(const Instruction &Inst) {
  const FunctionSamples *FS = findFunctionSamples(Inst);
  if (!FS)
    return std::error_code();

  const DebugLoc &DLoc = Inst.getDebugLoc();
  if (!DLoc)
    return std::error_code();

  const DILocation *DIL = DLoc;
  uint32_t LineOffset = FunctionSamples::getOffset(DIL);
  uint32_t Discriminator = DIL->getBaseDiscriminator();
  ErrorOr<uint64_t> R = FS->findSamplesAt(LineOffset, Discriminator);
  if (R) {
    bool FirstMark =
        CoverageTracker.markSamplesUsed(FS, LineOffset, Discriminator, R.get());
    if (FirstMark) {
      ORE->emit([&]() {
        OptimizationRemarkAnalysis Remark(DEBUG_TYPE, "AppliedSamples", &Inst);
        Remark << "Applied " << ore::NV("NumSamples", *R);
        Remark << " samples from profile (offset: ";
        Remark << ore::NV("LineOffset", LineOffset);
        if (Discriminator) {
          Remark << ".";
          Remark << ore::NV("Discriminator", Discriminator);
        }
        Remark << ")";
        return Remark;
      });
    }
    LLVM_DEBUG(dbgs() << "    " << DLoc.getLine() << "."
                      << DIL->getBaseDiscriminator() << ":" << Inst
                      << " (line offset: " << LineOffset << "."
                      << DIL->getBaseDiscriminator() << " - weight: " << R.get()
                      << ")\n");
  }
  return R;
}

ErrorOr<uint64_t> SampleProfileLoader::getProbeWeight(const Instruction &Inst) {
  assert(FunctionSamples::ProfileIsProbeBased &&
         "Profile is not pseudo probe based");
  Optional<PseudoProbe> Probe = extractProbe(Inst);
  if (!Probe)
    return std::error_code();

  const FunctionSamples *FS = findFunctionSamples(Inst);
  if (!FS)
    return std::error_code();

  // If a direct call/invoke instruction is inlined in profile
  // (findCalleeFunctionSamples returns non-empty result), but not inlined here,
  // it means that the inlined callsite has no sample, thus the call
  // instruction should have 0 count.
  if (const auto *CB = dyn_cast<CallBase>(&Inst))
    if (!CB->isIndirectCall() && findCalleeFunctionSamples(*CB))
      return 0;

  const ErrorOr<uint64_t> &R = FS->findSamplesAt(Probe->Id, 0);
  if (R) {
    uint64_t Samples = R.get() * Probe->Factor;
    bool FirstMark = CoverageTracker.markSamplesUsed(FS, Probe->Id, 0, Samples);
    if (FirstMark) {
      ORE->emit([&]() {
        OptimizationRemarkAnalysis Remark(DEBUG_TYPE, "AppliedSamples", &Inst);
        Remark << "Applied " << ore::NV("NumSamples", Samples);
        Remark << " samples from profile (ProbeId=";
        Remark << ore::NV("ProbeId", Probe->Id);
        Remark << ", Factor=";
        Remark << ore::NV("Factor", Probe->Factor);
        Remark << ", OriginalSamples=";
        Remark << ore::NV("OriginalSamples", R.get());
        Remark << ")";
        return Remark;
      });
    }
    LLVM_DEBUG(dbgs() << "    " << Probe->Id << ":" << Inst
                      << " - weight: " << R.get() << " - factor: "
                      << format("%0.2f", Probe->Factor) << ")\n");
    return Samples;
  }
  return R;
}

/// Compute the weight of a basic block.
///
/// The weight of basic block \p BB is the maximum weight of all the
/// instructions in BB.
///
/// \param BB The basic block to query.
///
/// \returns the weight for \p BB.
ErrorOr<uint64_t>
SampleProfileLoaderBaseImpl::getBlockWeight(const BasicBlock *BB) {
  uint64_t Max = 0;
  bool HasWeight = false;
  for (auto &I : BB->getInstList()) {
    const ErrorOr<uint64_t> &R = getInstWeight(I);
    if (R) {
      Max = std::max(Max, R.get());
      HasWeight = true;
    }
  }
  return HasWeight ? ErrorOr<uint64_t>(Max) : std::error_code();
}

/// Compute and store the weights of every basic block.
///
/// This populates the BlockWeights map by computing
/// the weights of every basic block in the CFG.
///
/// \param F The function to query.
bool SampleProfileLoaderBaseImpl::computeBlockWeights(Function &F) {
  bool Changed = false;
  LLVM_DEBUG(dbgs() << "Block weights\n");
  for (const auto &BB : F) {
    ErrorOr<uint64_t> Weight = getBlockWeight(&BB);
    if (Weight) {
      BlockWeights[&BB] = Weight.get();
      VisitedBlocks.insert(&BB);
      Changed = true;
    }
    LLVM_DEBUG(printBlockWeight(dbgs(), &BB));
  }

  return Changed;
}

/// Get the FunctionSamples for a call instruction.
///
/// The FunctionSamples of a call/invoke instruction \p Inst is the inlined
/// instance in which that call instruction is calling to. It contains
/// all samples that resides in the inlined instance. We first find the
/// inlined instance in which the call instruction is from, then we
/// traverse its children to find the callsite with the matching
/// location.
///
/// \param Inst Call/Invoke instruction to query.
///
/// \returns The FunctionSamples pointer to the inlined instance.
const FunctionSamples *
SampleProfileLoader::findCalleeFunctionSamples(const CallBase &Inst) const {
  const DILocation *DIL = Inst.getDebugLoc();
  if (!DIL) {
    return nullptr;
  }

  StringRef CalleeName;
  if (Function *Callee = Inst.getCalledFunction())
    CalleeName = FunctionSamples::getCanonicalFnName(*Callee);

  if (ProfileIsCS)
    return ContextTracker->getCalleeContextSamplesFor(Inst, CalleeName);

  const FunctionSamples *FS = findFunctionSamples(Inst);
  if (FS == nullptr)
    return nullptr;

  return FS->findFunctionSamplesAt(FunctionSamples::getCallSiteIdentifier(DIL),
                                   CalleeName, Reader->getRemapper());
}

/// Returns a vector of FunctionSamples that are the indirect call targets
/// of \p Inst. The vector is sorted by the total number of samples. Stores
/// the total call count of the indirect call in \p Sum.
std::vector<const FunctionSamples *>
SampleProfileLoader::findIndirectCallFunctionSamples(
    const Instruction &Inst, uint64_t &Sum) const {
  const DILocation *DIL = Inst.getDebugLoc();
  std::vector<const FunctionSamples *> R;

  if (!DIL) {
    return R;
  }

  auto FSCompare = [](const FunctionSamples *L, const FunctionSamples *R) {
    assert(L && R && "Expect non-null FunctionSamples");
    if (L->getEntrySamples() != R->getEntrySamples())
      return L->getEntrySamples() > R->getEntrySamples();
    return FunctionSamples::getGUID(L->getName()) <
           FunctionSamples::getGUID(R->getName());
  };

  if (ProfileIsCS) {
    auto CalleeSamples =
        ContextTracker->getIndirectCalleeContextSamplesFor(DIL);
    if (CalleeSamples.empty())
      return R;

    // For CSSPGO, we only use target context profile's entry count
    // as that already includes both inlined callee and non-inlined ones..
    Sum = 0;
    for (const auto *const FS : CalleeSamples) {
      Sum += FS->getEntrySamples();
      R.push_back(FS);
    }
    llvm::sort(R, FSCompare);
    return R;
  }

  const FunctionSamples *FS = findFunctionSamples(Inst);
  if (FS == nullptr)
    return R;

  auto CallSite = FunctionSamples::getCallSiteIdentifier(DIL);
  auto T = FS->findCallTargetMapAt(CallSite);
  Sum = 0;
  if (T)
    for (const auto &T_C : T.get())
      Sum += T_C.second;
  if (const FunctionSamplesMap *M = FS->findFunctionSamplesMapAt(CallSite)) {
    if (M->empty())
      return R;
    for (const auto &NameFS : *M) {
      Sum += NameFS.second.getEntrySamples();
      R.push_back(&NameFS.second);
    }
    llvm::sort(R, FSCompare);
  }
  return R;
}

/// Get the FunctionSamples for an instruction.
///
/// The FunctionSamples of an instruction \p Inst is the inlined instance
/// in which that instruction is coming from. We traverse the inline stack
/// of that instruction, and match it with the tree nodes in the profile.
///
/// \param Inst Instruction to query.
///
/// \returns the FunctionSamples pointer to the inlined instance.
const FunctionSamples *SampleProfileLoaderBaseImpl::findFunctionSamples(
    const Instruction &Inst) const {
  const DILocation *DIL = Inst.getDebugLoc();
  if (!DIL)
    return Samples;

  auto it = DILocation2SampleMap.try_emplace(DIL, nullptr);
  if (it.second) {
    it.first->second = Samples->findFunctionSamples(DIL, Reader->getRemapper());
  }
  return it.first->second;
}

const FunctionSamples *
SampleProfileLoader::findFunctionSamples(const Instruction &Inst) const {
  if (FunctionSamples::ProfileIsProbeBased) {
    Optional<PseudoProbe> Probe = extractProbe(Inst);
    if (!Probe)
      return nullptr;
  }

  const DILocation *DIL = Inst.getDebugLoc();
  if (!DIL)
    return Samples;

  auto it = DILocation2SampleMap.try_emplace(DIL,nullptr);
  if (it.second) {
    if (ProfileIsCS)
      it.first->second = ContextTracker->getContextSamplesFor(DIL);
    else
      it.first->second =
          Samples->findFunctionSamples(DIL, Reader->getRemapper());
  }
  return it.first->second;
}

/// Attempt to promote indirect call and also inline the promoted call.
///
/// \param F  Caller function.
/// \param Candidate  ICP and inline candidate.
/// \param Sum  Sum of target counts for indirect call.
/// \param PromotedInsns  Map to keep track of indirect call already processed.
/// \param InlinedCallSite  Output vector for new call sites exposed after
/// inlining.
bool SampleProfileLoader::tryPromoteAndInlineCandidate(
    Function &F, InlineCandidate &Candidate, uint64_t SumOrigin, uint64_t &Sum,
    DenseSet<Instruction *> &PromotedInsns,
    SmallVector<CallBase *, 8> *InlinedCallSite) {
  const char *Reason = "Callee function not available";
  // R->getValue() != &F is to prevent promoting a recursive call.
  // If it is a recursive call, we do not inline it as it could bloat
  // the code exponentially. There is way to better handle this, e.g.
  // clone the caller first, and inline the cloned caller if it is
  // recursive. As llvm does not inline recursive calls, we will
  // simply ignore it instead of handling it explicitly.
  auto R = SymbolMap.find(Candidate.CalleeSamples->getFuncName());
  if (R != SymbolMap.end() && R->getValue() &&
      !R->getValue()->isDeclaration() && R->getValue()->getSubprogram() &&
      R->getValue()->hasFnAttribute("use-sample-profile") &&
      R->getValue() != &F &&
      isLegalToPromote(*Candidate.CallInstr, R->getValue(), &Reason)) {
    auto *DI =
        &pgo::promoteIndirectCall(*Candidate.CallInstr, R->getValue(),
                                  Candidate.CallsiteCount, Sum, false, ORE);
    if (DI) {
      Sum -= Candidate.CallsiteCount;
      // Prorate the indirect callsite distribution.
      // Do not update the promoted direct callsite distribution at this
      // point since the original distribution combined with the callee
      // profile will be used to prorate callsites from the callee if
      // inlined. Once not inlined, the direct callsite distribution should
      // be prorated so that the it will reflect the real callsite counts.
      setProbeDistributionFactor(*Candidate.CallInstr,
                                 Candidate.CallsiteDistribution * Sum /
                                     SumOrigin);
      PromotedInsns.insert(Candidate.CallInstr);
      Candidate.CallInstr = DI;
      if (isa<CallInst>(DI) || isa<InvokeInst>(DI)) {
        bool Inlined = tryInlineCandidate(Candidate, InlinedCallSite);
        if (!Inlined) {
          // Prorate the direct callsite distribution so that it reflects real
          // callsite counts.
          setProbeDistributionFactor(*DI, Candidate.CallsiteDistribution *
                                              Candidate.CallsiteCount /
                                              SumOrigin);
        }
        return Inlined;
      }
    }
  } else {
    LLVM_DEBUG(dbgs() << "\nFailed to promote indirect call to "
                      << Candidate.CalleeSamples->getFuncName() << " because "
                      << Reason << "\n");
  }
  return false;
}

bool SampleProfileLoader::shouldInlineColdCallee(CallBase &CallInst) {
  if (!ProfileSizeInline)
    return false;

  Function *Callee = CallInst.getCalledFunction();
  if (Callee == nullptr)
    return false;

  InlineCost Cost = getInlineCost(CallInst, getInlineParams(), GetTTI(*Callee),
                                  GetAC, GetTLI);

  if (Cost.isNever())
    return false;

  if (Cost.isAlways())
    return true;

  return Cost.getCost() <= SampleColdCallSiteThreshold;
}

void SampleProfileLoader::emitOptimizationRemarksForInlineCandidates(
    const SmallVectorImpl<CallBase *> &Candidates, const Function &F,
    bool Hot) {
  for (auto I : Candidates) {
    Function *CalledFunction = I->getCalledFunction();
    if (CalledFunction) {
      ORE->emit(OptimizationRemarkAnalysis(CSINLINE_DEBUG, "InlineAttempt",
                                           I->getDebugLoc(), I->getParent())
                << "previous inlining reattempted for "
                << (Hot ? "hotness: '" : "size: '")
                << ore::NV("Callee", CalledFunction) << "' into '"
                << ore::NV("Caller", &F) << "'");
    }
  }
}

/// Iteratively inline hot callsites of a function.
///
/// Iteratively traverse all callsites of the function \p F, and find if
/// the corresponding inlined instance exists and is hot in profile. If
/// it is hot enough, inline the callsites and adds new callsites of the
/// callee into the caller. If the call is an indirect call, first promote
/// it to direct call. Each indirect call is limited with a single target.
///
/// \param F function to perform iterative inlining.
/// \param InlinedGUIDs a set to be updated to include all GUIDs that are
///     inlined in the profiled binary.
///
/// \returns True if there is any inline happened.
bool SampleProfileLoader::inlineHotFunctions(
    Function &F, DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
  DenseSet<Instruction *> PromotedInsns;

  // ProfAccForSymsInList is used in callsiteIsHot. The assertion makes sure
  // Profile symbol list is ignored when profile-sample-accurate is on.
  assert((!ProfAccForSymsInList ||
          (!ProfileSampleAccurate &&
           !F.hasFnAttribute("profile-sample-accurate"))) &&
         "ProfAccForSymsInList should be false when profile-sample-accurate "
         "is enabled");

  DenseMap<CallBase *, const FunctionSamples *> LocalNotInlinedCallSites;
  bool Changed = false;
  bool LocalChanged = true;
  while (LocalChanged) {
    LocalChanged = false;
    SmallVector<CallBase *, 10> CIS;
    for (auto &BB : F) {
      bool Hot = false;
      SmallVector<CallBase *, 10> AllCandidates;
      SmallVector<CallBase *, 10> ColdCandidates;
      for (auto &I : BB.getInstList()) {
        const FunctionSamples *FS = nullptr;
        if (auto *CB = dyn_cast<CallBase>(&I)) {
          if (!isa<IntrinsicInst>(I) && (FS = findCalleeFunctionSamples(*CB))) {
            assert((!FunctionSamples::UseMD5 || FS->GUIDToFuncNameMap) &&
                   "GUIDToFuncNameMap has to be populated");
            AllCandidates.push_back(CB);
            if (FS->getEntrySamples() > 0 || ProfileIsCS)
              LocalNotInlinedCallSites.try_emplace(CB, FS);
            if (callsiteIsHot(FS, PSI, ProfAccForSymsInList))
              Hot = true;
            else if (shouldInlineColdCallee(*CB))
              ColdCandidates.push_back(CB);
          }
        }
      }
      if (Hot || ExternalInlineAdvisor) {
        CIS.insert(CIS.begin(), AllCandidates.begin(), AllCandidates.end());
        emitOptimizationRemarksForInlineCandidates(AllCandidates, F, true);
      } else {
        CIS.insert(CIS.begin(), ColdCandidates.begin(), ColdCandidates.end());
        emitOptimizationRemarksForInlineCandidates(ColdCandidates, F, false);
      }
    }
    for (CallBase *I : CIS) {
      Function *CalledFunction = I->getCalledFunction();
      InlineCandidate Candidate = {
          I,
          LocalNotInlinedCallSites.count(I) ? LocalNotInlinedCallSites[I]
                                            : nullptr,
          0 /* dummy count */, 1.0 /* dummy distribution factor */};
      // Do not inline recursive calls.
      if (CalledFunction == &F)
        continue;
      if (I->isIndirectCall()) {
        if (PromotedInsns.count(I))
          continue;
        uint64_t Sum;
        for (const auto *FS : findIndirectCallFunctionSamples(*I, Sum)) {
          uint64_t SumOrigin = Sum;
          if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink) {
            FS->findInlinedFunctions(InlinedGUIDs, F.getParent(),
                                     PSI->getOrCompHotCountThreshold());
            continue;
          }
          if (!callsiteIsHot(FS, PSI, ProfAccForSymsInList))
            continue;

          Candidate = {I, FS, FS->getEntrySamples(), 1.0};
          if (tryPromoteAndInlineCandidate(F, Candidate, SumOrigin, Sum,
                                           PromotedInsns)) {
            LocalNotInlinedCallSites.erase(I);
            LocalChanged = true;
          }
        }
      } else if (CalledFunction && CalledFunction->getSubprogram() &&
                 !CalledFunction->isDeclaration()) {
        if (tryInlineCandidate(Candidate)) {
          LocalNotInlinedCallSites.erase(I);
          LocalChanged = true;
        }
      } else if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink) {
        findCalleeFunctionSamples(*I)->findInlinedFunctions(
            InlinedGUIDs, F.getParent(), PSI->getOrCompHotCountThreshold());
      }
    }
    Changed |= LocalChanged;
  }

  // For CS profile, profile for not inlined context will be merged when
  // base profile is being trieved
  if (ProfileIsCS)
    return Changed;

  // Accumulate not inlined callsite information into notInlinedSamples
  for (const auto &Pair : LocalNotInlinedCallSites) {
    CallBase *I = Pair.getFirst();
    Function *Callee = I->getCalledFunction();
    if (!Callee || Callee->isDeclaration())
      continue;

    ORE->emit(OptimizationRemarkAnalysis(CSINLINE_DEBUG, "NotInline",
                                         I->getDebugLoc(), I->getParent())
              << "previous inlining not repeated: '"
              << ore::NV("Callee", Callee) << "' into '"
              << ore::NV("Caller", &F) << "'");

    ++NumCSNotInlined;
    const FunctionSamples *FS = Pair.getSecond();
    if (FS->getTotalSamples() == 0 && FS->getEntrySamples() == 0) {
      continue;
    }

    if (ProfileMergeInlinee) {
      // A function call can be replicated by optimizations like callsite
      // splitting or jump threading and the replicates end up sharing the
      // sample nested callee profile instead of slicing the original inlinee's
      // profile. We want to do merge exactly once by filtering out callee
      // profiles with a non-zero head sample count.
      if (FS->getHeadSamples() == 0) {
        // Use entry samples as head samples during the merge, as inlinees
        // don't have head samples.
        const_cast<FunctionSamples *>(FS)->addHeadSamples(
            FS->getEntrySamples());

        // Note that we have to do the merge right after processing function.
        // This allows OutlineFS's profile to be used for annotation during
        // top-down processing of functions' annotation.
        FunctionSamples *OutlineFS = Reader->getOrCreateSamplesFor(*Callee);
        OutlineFS->merge(*FS);
      }
    } else {
      auto pair =
          notInlinedCallInfo.try_emplace(Callee, NotInlinedProfileInfo{0});
      pair.first->second.entryCount += FS->getEntrySamples();
    }
  }
  return Changed;
}

bool SampleProfileLoader::tryInlineCandidate(
    InlineCandidate &Candidate, SmallVector<CallBase *, 8> *InlinedCallSites) {

  CallBase &CB = *Candidate.CallInstr;
  Function *CalledFunction = CB.getCalledFunction();
  assert(CalledFunction && "Expect a callee with definition");
  DebugLoc DLoc = CB.getDebugLoc();
  BasicBlock *BB = CB.getParent();

  InlineCost Cost = shouldInlineCandidate(Candidate);
  if (Cost.isNever()) {
    ORE->emit(OptimizationRemarkAnalysis(CSINLINE_DEBUG, "InlineFail", DLoc, BB)
              << "incompatible inlining");
    return false;
  }

  if (!Cost)
    return false;

  InlineFunctionInfo IFI(nullptr, GetAC);
  if (InlineFunction(CB, IFI).isSuccess()) {
    // The call to InlineFunction erases I, so we can't pass it here.
    emitInlinedInto(*ORE, DLoc, BB, *CalledFunction, *BB->getParent(), Cost,
                    true, CSINLINE_DEBUG);

    // Now populate the list of newly exposed call sites.
    if (InlinedCallSites) {
      InlinedCallSites->clear();
      for (auto &I : IFI.InlinedCallSites)
        InlinedCallSites->push_back(I);
    }

    if (ProfileIsCS)
      ContextTracker->markContextSamplesInlined(Candidate.CalleeSamples);
    ++NumCSInlined;

    // Prorate inlined probes for a duplicated inlining callsite which probably
    // has a distribution less than 100%. Samples for an inlinee should be
    // distributed among the copies of the original callsite based on each
    // callsite's distribution factor for counts accuracy. Note that an inlined
    // probe may come with its own distribution factor if it has been duplicated
    // in the inlinee body. The two factor are multiplied to reflect the
    // aggregation of duplication.
    if (Candidate.CallsiteDistribution < 1) {
      for (auto &I : IFI.InlinedCallSites) {
        if (Optional<PseudoProbe> Probe = extractProbe(*I))
          setProbeDistributionFactor(*I, Probe->Factor *
                                             Candidate.CallsiteDistribution);
      }
      NumDuplicatedInlinesite++;
    }

    return true;
  }
  return false;
}

bool SampleProfileLoader::getInlineCandidate(InlineCandidate *NewCandidate,
                                             CallBase *CB) {
  assert(CB && "Expect non-null call instruction");

  if (isa<IntrinsicInst>(CB))
    return false;

  // Find the callee's profile. For indirect call, find hottest target profile.
  const FunctionSamples *CalleeSamples = findCalleeFunctionSamples(*CB);
  if (!CalleeSamples)
    return false;

  float Factor = 1.0;
  if (Optional<PseudoProbe> Probe = extractProbe(*CB))
    Factor = Probe->Factor;

  uint64_t CallsiteCount = 0;
  ErrorOr<uint64_t> Weight = getBlockWeight(CB->getParent());
  if (Weight)
    CallsiteCount = Weight.get();
  if (CalleeSamples)
    CallsiteCount = std::max(
        CallsiteCount, uint64_t(CalleeSamples->getEntrySamples() * Factor));

  *NewCandidate = {CB, CalleeSamples, CallsiteCount, Factor};
  return true;
}

InlineCost
SampleProfileLoader::shouldInlineCandidate(InlineCandidate &Candidate) {
  std::unique_ptr<InlineAdvice> Advice = nullptr;
  if (ExternalInlineAdvisor) {
    Advice = ExternalInlineAdvisor->getAdvice(*Candidate.CallInstr);
    if (!Advice->isInliningRecommended()) {
      Advice->recordUnattemptedInlining();
      return InlineCost::getNever("not previously inlined");
    }
    Advice->recordInlining();
    return InlineCost::getAlways("previously inlined");
  }

  // Adjust threshold based on call site hotness, only do this for callsite
  // prioritized inliner because otherwise cost-benefit check is done earlier.
  int SampleThreshold = SampleColdCallSiteThreshold;
  if (CallsitePrioritizedInline) {
    if (Candidate.CallsiteCount > PSI->getHotCountThreshold())
      SampleThreshold = SampleHotCallSiteThreshold;
    else if (!ProfileSizeInline)
      return InlineCost::getNever("cold callsite");
  }

  Function *Callee = Candidate.CallInstr->getCalledFunction();
  assert(Callee && "Expect a definition for inline candidate of direct call");

  InlineParams Params = getInlineParams();
  Params.ComputeFullInlineCost = true;
  // Checks if there is anything in the reachable portion of the callee at
  // this callsite that makes this inlining potentially illegal. Need to
  // set ComputeFullInlineCost, otherwise getInlineCost may return early
  // when cost exceeds threshold without checking all IRs in the callee.
  // The acutal cost does not matter because we only checks isNever() to
  // see if it is legal to inline the callsite.
  InlineCost Cost = getInlineCost(*Candidate.CallInstr, Callee, Params,
                                  GetTTI(*Callee), GetAC, GetTLI);

  // Honor always inline and never inline from call analyzer
  if (Cost.isNever() || Cost.isAlways())
    return Cost;

  // For old FDO inliner, we inline the call site as long as cost is not
  // "Never". The cost-benefit check is done earlier.
  if (!CallsitePrioritizedInline) {
    return InlineCost::get(Cost.getCost(), INT_MAX);
  }

  // Otherwise only use the cost from call analyzer, but overwite threshold with
  // Sample PGO threshold.
  return InlineCost::get(Cost.getCost(), SampleThreshold);
}

bool SampleProfileLoader::inlineHotFunctionsWithPriority(
    Function &F, DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
  DenseSet<Instruction *> PromotedInsns;
  assert(ProfileIsCS && "Prioritiy based inliner only works with CSSPGO now");

  // ProfAccForSymsInList is used in callsiteIsHot. The assertion makes sure
  // Profile symbol list is ignored when profile-sample-accurate is on.
  assert((!ProfAccForSymsInList ||
          (!ProfileSampleAccurate &&
           !F.hasFnAttribute("profile-sample-accurate"))) &&
         "ProfAccForSymsInList should be false when profile-sample-accurate "
         "is enabled");

  // Populating worklist with initial call sites from root inliner, along
  // with call site weights.
  CandidateQueue CQueue;
  InlineCandidate NewCandidate;
  for (auto &BB : F) {
    for (auto &I : BB.getInstList()) {
      auto *CB = dyn_cast<CallBase>(&I);
      if (!CB)
        continue;
      if (getInlineCandidate(&NewCandidate, CB))
        CQueue.push(NewCandidate);
    }
  }

  // Cap the size growth from profile guided inlining. This is needed even
  // though cost of each inline candidate already accounts for callee size,
  // because with top-down inlining, we can grow inliner size significantly
  // with large number of smaller inlinees each pass the cost check.
  assert(ProfileInlineLimitMax >= ProfileInlineLimitMin &&
         "Max inline size limit should not be smaller than min inline size "
         "limit.");
  unsigned SizeLimit = F.getInstructionCount() * ProfileInlineGrowthLimit;
  SizeLimit = std::min(SizeLimit, (unsigned)ProfileInlineLimitMax);
  SizeLimit = std::max(SizeLimit, (unsigned)ProfileInlineLimitMin);
  if (ExternalInlineAdvisor)
    SizeLimit = std::numeric_limits<unsigned>::max();

  // Perform iterative BFS call site prioritized inlining
  bool Changed = false;
  while (!CQueue.empty() && F.getInstructionCount() < SizeLimit) {
    InlineCandidate Candidate = CQueue.top();
    CQueue.pop();
    CallBase *I = Candidate.CallInstr;
    Function *CalledFunction = I->getCalledFunction();

    if (CalledFunction == &F)
      continue;
    if (I->isIndirectCall()) {
      if (PromotedInsns.count(I))
        continue;
      uint64_t Sum;
      auto CalleeSamples = findIndirectCallFunctionSamples(*I, Sum);
      uint64_t SumOrigin = Sum;
      Sum *= Candidate.CallsiteDistribution;
      for (const auto *FS : CalleeSamples) {
        // TODO: Consider disable pre-lTO ICP for MonoLTO as well
        if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink) {
          FS->findInlinedFunctions(InlinedGUIDs, F.getParent(),
                                   PSI->getOrCompHotCountThreshold());
          continue;
        }
        uint64_t EntryCountDistributed =
            FS->getEntrySamples() * Candidate.CallsiteDistribution;
        // In addition to regular inline cost check, we also need to make sure
        // ICP isn't introducing excessive speculative checks even if individual
        // target looks beneficial to promote and inline. That means we should
        // only do ICP when there's a small number dominant targets.
        if (EntryCountDistributed < SumOrigin / ProfileICPThreshold)
          break;
        // TODO: Fix CallAnalyzer to handle all indirect calls.
        // For indirect call, we don't run CallAnalyzer to get InlineCost
        // before actual inlining. This is because we could see two different
        // types from the same definition, which makes CallAnalyzer choke as
        // it's expecting matching parameter type on both caller and callee
        // side. See example from PR18962 for the triggering cases (the bug was
        // fixed, but we generate different types).
        if (!PSI->isHotCount(EntryCountDistributed))
          break;
        SmallVector<CallBase *, 8> InlinedCallSites;
        // Attach function profile for promoted indirect callee, and update
        // call site count for the promoted inline candidate too.
        Candidate = {I, FS, EntryCountDistributed,
                     Candidate.CallsiteDistribution};
        if (tryPromoteAndInlineCandidate(F, Candidate, SumOrigin, Sum,
                                         PromotedInsns, &InlinedCallSites)) {
          for (auto *CB : InlinedCallSites) {
            if (getInlineCandidate(&NewCandidate, CB))
              CQueue.emplace(NewCandidate);
          }
          Changed = true;
        }
      }
    } else if (CalledFunction && CalledFunction->getSubprogram() &&
               !CalledFunction->isDeclaration()) {
      SmallVector<CallBase *, 8> InlinedCallSites;
      if (tryInlineCandidate(Candidate, &InlinedCallSites)) {
        for (auto *CB : InlinedCallSites) {
          if (getInlineCandidate(&NewCandidate, CB))
            CQueue.emplace(NewCandidate);
        }
        Changed = true;
      }
    } else if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink) {
      findCalleeFunctionSamples(*I)->findInlinedFunctions(
          InlinedGUIDs, F.getParent(), PSI->getOrCompHotCountThreshold());
    }
  }

  if (!CQueue.empty()) {
    if (SizeLimit == (unsigned)ProfileInlineLimitMax)
      ++NumCSInlinedHitMaxLimit;
    else if (SizeLimit == (unsigned)ProfileInlineLimitMin)
      ++NumCSInlinedHitMinLimit;
    else
      ++NumCSInlinedHitGrowthLimit;
  }

  return Changed;
}

/// Find equivalence classes for the given block.
///
/// This finds all the blocks that are guaranteed to execute the same
/// number of times as \p BB1. To do this, it traverses all the
/// descendants of \p BB1 in the dominator or post-dominator tree.
///
/// A block BB2 will be in the same equivalence class as \p BB1 if
/// the following holds:
///
/// 1- \p BB1 is a descendant of BB2 in the opposite tree. So, if BB2
///    is a descendant of \p BB1 in the dominator tree, then BB2 should
///    dominate BB1 in the post-dominator tree.
///
/// 2- Both BB2 and \p BB1 must be in the same loop.
///
/// For every block BB2 that meets those two requirements, we set BB2's
/// equivalence class to \p BB1.
///
/// \param BB1  Block to check.
/// \param Descendants  Descendants of \p BB1 in either the dom or pdom tree.
/// \param DomTree  Opposite dominator tree. If \p Descendants is filled
///                 with blocks from \p BB1's dominator tree, then
///                 this is the post-dominator tree, and vice versa.
template <bool IsPostDom>
void SampleProfileLoaderBaseImpl::findEquivalencesFor(
    BasicBlock *BB1, ArrayRef<BasicBlock *> Descendants,
    DominatorTreeBase<BasicBlock, IsPostDom> *DomTree) {
  const BasicBlock *EC = EquivalenceClass[BB1];
  uint64_t Weight = BlockWeights[EC];
  for (const auto *BB2 : Descendants) {
    bool IsDomParent = DomTree->dominates(BB2, BB1);
    bool IsInSameLoop = LI->getLoopFor(BB1) == LI->getLoopFor(BB2);
    if (BB1 != BB2 && IsDomParent && IsInSameLoop) {
      EquivalenceClass[BB2] = EC;
      // If BB2 is visited, then the entire EC should be marked as visited.
      if (VisitedBlocks.count(BB2)) {
        VisitedBlocks.insert(EC);
      }

      // If BB2 is heavier than BB1, make BB2 have the same weight
      // as BB1.
      //
      // Note that we don't worry about the opposite situation here
      // (when BB2 is lighter than BB1). We will deal with this
      // during the propagation phase. Right now, we just want to
      // make sure that BB1 has the largest weight of all the
      // members of its equivalence set.
      Weight = std::max(Weight, BlockWeights[BB2]);
    }
  }
  if (EC == &EC->getParent()->getEntryBlock()) {
    BlockWeights[EC] = Samples->getHeadSamples() + 1;
  } else {
    BlockWeights[EC] = Weight;
  }
}

/// Find equivalence classes.
///
/// Since samples may be missing from blocks, we can fill in the gaps by setting
/// the weights of all the blocks in the same equivalence class to the same
/// weight. To compute the concept of equivalence, we use dominance and loop
/// information. Two blocks B1 and B2 are in the same equivalence class if B1
/// dominates B2, B2 post-dominates B1 and both are in the same loop.
///
/// \param F The function to query.
void SampleProfileLoaderBaseImpl::findEquivalenceClasses(Function &F) {
  SmallVector<BasicBlock *, 8> DominatedBBs;
  LLVM_DEBUG(dbgs() << "\nBlock equivalence classes\n");
  // Find equivalence sets based on dominance and post-dominance information.
  for (auto &BB : F) {
    BasicBlock *BB1 = &BB;

    // Compute BB1's equivalence class once.
    if (EquivalenceClass.count(BB1)) {
      LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1));
      continue;
    }

    // By default, blocks are in their own equivalence class.
    EquivalenceClass[BB1] = BB1;

    // Traverse all the blocks dominated by BB1. We are looking for
    // every basic block BB2 such that:
    //
    // 1- BB1 dominates BB2.
    // 2- BB2 post-dominates BB1.
    // 3- BB1 and BB2 are in the same loop nest.
    //
    // If all those conditions hold, it means that BB2 is executed
    // as many times as BB1, so they are placed in the same equivalence
    // class by making BB2's equivalence class be BB1.
    DominatedBBs.clear();
    DT->getDescendants(BB1, DominatedBBs);
    findEquivalencesFor(BB1, DominatedBBs, PDT.get());

    LLVM_DEBUG(printBlockEquivalence(dbgs(), BB1));
  }

  // Assign weights to equivalence classes.
  //
  // All the basic blocks in the same equivalence class will execute
  // the same number of times. Since we know that the head block in
  // each equivalence class has the largest weight, assign that weight
  // to all the blocks in that equivalence class.
  LLVM_DEBUG(
      dbgs() << "\nAssign the same weight to all blocks in the same class\n");
  for (auto &BI : F) {
    const BasicBlock *BB = &BI;
    const BasicBlock *EquivBB = EquivalenceClass[BB];
    if (BB != EquivBB)
      BlockWeights[BB] = BlockWeights[EquivBB];
    LLVM_DEBUG(printBlockWeight(dbgs(), BB));
  }
}

/// Visit the given edge to decide if it has a valid weight.
///
/// If \p E has not been visited before, we copy to \p UnknownEdge
/// and increment the count of unknown edges.
///
/// \param E  Edge to visit.
/// \param NumUnknownEdges  Current number of unknown edges.
/// \param UnknownEdge  Set if E has not been visited before.
///
/// \returns E's weight, if known. Otherwise, return 0.
uint64_t SampleProfileLoaderBaseImpl::visitEdge(Edge E,
                                                unsigned *NumUnknownEdges,
                                                Edge *UnknownEdge) {
  if (!VisitedEdges.count(E)) {
    (*NumUnknownEdges)++;
    *UnknownEdge = E;
    return 0;
  }

  return EdgeWeights[E];
}

/// Propagate weights through incoming/outgoing edges.
///
/// If the weight of a basic block is known, and there is only one edge
/// with an unknown weight, we can calculate the weight of that edge.
///
/// Similarly, if all the edges have a known count, we can calculate the
/// count of the basic block, if needed.
///
/// \param F  Function to process.
/// \param UpdateBlockCount  Whether we should update basic block counts that
///                          has already been annotated.
///
/// \returns  True if new weights were assigned to edges or blocks.
bool SampleProfileLoaderBaseImpl::propagateThroughEdges(Function &F,
                                                        bool UpdateBlockCount) {
  bool Changed = false;
  LLVM_DEBUG(dbgs() << "\nPropagation through edges\n");
  for (const auto &BI : F) {
    const BasicBlock *BB = &BI;
    const BasicBlock *EC = EquivalenceClass[BB];

    // Visit all the predecessor and successor edges to determine
    // which ones have a weight assigned already. Note that it doesn't
    // matter that we only keep track of a single unknown edge. The
    // only case we are interested in handling is when only a single
    // edge is unknown (see setEdgeOrBlockWeight).
    for (unsigned i = 0; i < 2; i++) {
      uint64_t TotalWeight = 0;
      unsigned NumUnknownEdges = 0, NumTotalEdges = 0;
      Edge UnknownEdge, SelfReferentialEdge, SingleEdge;

      if (i == 0) {
        // First, visit all predecessor edges.
        NumTotalEdges = Predecessors[BB].size();
        for (auto *Pred : Predecessors[BB]) {
          Edge E = std::make_pair(Pred, BB);
          TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
          if (E.first == E.second)
            SelfReferentialEdge = E;
        }
        if (NumTotalEdges == 1) {
          SingleEdge = std::make_pair(Predecessors[BB][0], BB);
        }
      } else {
        // On the second round, visit all successor edges.
        NumTotalEdges = Successors[BB].size();
        for (auto *Succ : Successors[BB]) {
          Edge E = std::make_pair(BB, Succ);
          TotalWeight += visitEdge(E, &NumUnknownEdges, &UnknownEdge);
        }
        if (NumTotalEdges == 1) {
          SingleEdge = std::make_pair(BB, Successors[BB][0]);
        }
      }

      // After visiting all the edges, there are three cases that we
      // can handle immediately:
      //
      // - All the edge weights are known (i.e., NumUnknownEdges == 0).
      //   In this case, we simply check that the sum of all the edges
      //   is the same as BB's weight. If not, we change BB's weight
      //   to match. Additionally, if BB had not been visited before,
      //   we mark it visited.
      //
      // - Only one edge is unknown and BB has already been visited.
      //   In this case, we can compute the weight of the edge by
      //   subtracting the total block weight from all the known
      //   edge weights. If the edges weight more than BB, then the
      //   edge of the last remaining edge is set to zero.
      //
      // - There exists a self-referential edge and the weight of BB is
      //   known. In this case, this edge can be based on BB's weight.
      //   We add up all the other known edges and set the weight on
      //   the self-referential edge as we did in the previous case.
      //
      // In any other case, we must continue iterating. Eventually,
      // all edges will get a weight, or iteration will stop when
      // it reaches SampleProfileMaxPropagateIterations.
      if (NumUnknownEdges <= 1) {
        uint64_t &BBWeight = BlockWeights[EC];
        if (NumUnknownEdges == 0) {
          if (!VisitedBlocks.count(EC)) {
            // If we already know the weight of all edges, the weight of the
            // basic block can be computed. It should be no larger than the sum
            // of all edge weights.
            if (TotalWeight > BBWeight) {
              BBWeight = TotalWeight;
              Changed = true;
              LLVM_DEBUG(dbgs() << "All edge weights for " << BB->getName()
                                << " known. Set weight for block: ";
                         printBlockWeight(dbgs(), BB););
            }
          } else if (NumTotalEdges == 1 &&
                     EdgeWeights[SingleEdge] < BlockWeights[EC]) {
            // If there is only one edge for the visited basic block, use the
            // block weight to adjust edge weight if edge weight is smaller.
            EdgeWeights[SingleEdge] = BlockWeights[EC];
            Changed = true;
          }
        } else if (NumUnknownEdges == 1 && VisitedBlocks.count(EC)) {
          // If there is a single unknown edge and the block has been
          // visited, then we can compute E's weight.
          if (BBWeight >= TotalWeight)
            EdgeWeights[UnknownEdge] = BBWeight - TotalWeight;
          else
            EdgeWeights[UnknownEdge] = 0;
          const BasicBlock *OtherEC;
          if (i == 0)
            OtherEC = EquivalenceClass[UnknownEdge.first];
          else
            OtherEC = EquivalenceClass[UnknownEdge.second];
          // Edge weights should never exceed the BB weights it connects.
          if (VisitedBlocks.count(OtherEC) &&
              EdgeWeights[UnknownEdge] > BlockWeights[OtherEC])
            EdgeWeights[UnknownEdge] = BlockWeights[OtherEC];
          VisitedEdges.insert(UnknownEdge);
          Changed = true;
          LLVM_DEBUG(dbgs() << "Set weight for edge: ";
                     printEdgeWeight(dbgs(), UnknownEdge));
        }
      } else if (VisitedBlocks.count(EC) && BlockWeights[EC] == 0) {
        // If a block Weights 0, all its in/out edges should weight 0.
        if (i == 0) {
          for (auto *Pred : Predecessors[BB]) {
            Edge E = std::make_pair(Pred, BB);
            EdgeWeights[E] = 0;
            VisitedEdges.insert(E);
          }
        } else {
          for (auto *Succ : Successors[BB]) {
            Edge E = std::make_pair(BB, Succ);
            EdgeWeights[E] = 0;
            VisitedEdges.insert(E);
          }
        }
      } else if (SelfReferentialEdge.first && VisitedBlocks.count(EC)) {
        uint64_t &BBWeight = BlockWeights[BB];
        // We have a self-referential edge and the weight of BB is known.
        if (BBWeight >= TotalWeight)
          EdgeWeights[SelfReferentialEdge] = BBWeight - TotalWeight;
        else
          EdgeWeights[SelfReferentialEdge] = 0;
        VisitedEdges.insert(SelfReferentialEdge);
        Changed = true;
        LLVM_DEBUG(dbgs() << "Set self-referential edge weight to: ";
                   printEdgeWeight(dbgs(), SelfReferentialEdge));
      }
      if (UpdateBlockCount && !VisitedBlocks.count(EC) && TotalWeight > 0) {
        BlockWeights[EC] = TotalWeight;
        VisitedBlocks.insert(EC);
        Changed = true;
      }
    }
  }

  return Changed;
}

/// Build in/out edge lists for each basic block in the CFG.
///
/// We are interested in unique edges. If a block B1 has multiple
/// edges to another block B2, we only add a single B1->B2 edge.
void SampleProfileLoaderBaseImpl::buildEdges(Function &F) {
  for (auto &BI : F) {
    BasicBlock *B1 = &BI;

    // Add predecessors for B1.
    SmallPtrSet<BasicBlock *, 16> Visited;
    if (!Predecessors[B1].empty())
      llvm_unreachable("Found a stale predecessors list in a basic block.");
    for (BasicBlock *B2 : predecessors(B1))
      if (Visited.insert(B2).second)
        Predecessors[B1].push_back(B2);

    // Add successors for B1.
    Visited.clear();
    if (!Successors[B1].empty())
      llvm_unreachable("Found a stale successors list in a basic block.");
    for (BasicBlock *B2 : successors(B1))
      if (Visited.insert(B2).second)
        Successors[B1].push_back(B2);
  }
}

/// Returns the sorted CallTargetMap \p M by count in descending order.
static SmallVector<InstrProfValueData, 2> GetSortedValueDataFromCallTargets(
    const SampleRecord::CallTargetMap & M) {
  SmallVector<InstrProfValueData, 2> R;
  for (const auto &I : SampleRecord::SortCallTargets(M)) {
    R.emplace_back(InstrProfValueData{FunctionSamples::getGUID(I.first), I.second});
  }
  return R;
}

/// Propagate weights into edges
///
/// The following rules are applied to every block BB in the CFG:
///
/// - If BB has a single predecessor/successor, then the weight
///   of that edge is the weight of the block.
///
/// - If all incoming or outgoing edges are known except one, and the
///   weight of the block is already known, the weight of the unknown
///   edge will be the weight of the block minus the sum of all the known
///   edges. If the sum of all the known edges is larger than BB's weight,
///   we set the unknown edge weight to zero.
///
/// - If there is a self-referential edge, and the weight of the block is
///   known, the weight for that edge is set to the weight of the block
///   minus the weight of the other incoming edges to that block (if
///   known).
void SampleProfileLoaderBaseImpl::propagateWeights(Function &F) {
  bool Changed = true;
  unsigned I = 0;

  // If BB weight is larger than its corresponding loop's header BB weight,
  // use the BB weight to replace the loop header BB weight.
  for (auto &BI : F) {
    BasicBlock *BB = &BI;
    Loop *L = LI->getLoopFor(BB);
    if (!L) {
      continue;
    }
    BasicBlock *Header = L->getHeader();
    if (Header && BlockWeights[BB] > BlockWeights[Header]) {
      BlockWeights[Header] = BlockWeights[BB];
    }
  }

  // Before propagation starts, build, for each block, a list of
  // unique predecessors and successors. This is necessary to handle
  // identical edges in multiway branches. Since we visit all blocks and all
  // edges of the CFG, it is cleaner to build these lists once at the start
  // of the pass.
  buildEdges(F);

  // Propagate until we converge or we go past the iteration limit.
  while (Changed && I++ < SampleProfileMaxPropagateIterations) {
    Changed = propagateThroughEdges(F, false);
  }

  // The first propagation propagates BB counts from annotated BBs to unknown
  // BBs. The 2nd propagation pass resets edges weights, and use all BB weights
  // to propagate edge weights.
  VisitedEdges.clear();
  Changed = true;
  while (Changed && I++ < SampleProfileMaxPropagateIterations) {
    Changed = propagateThroughEdges(F, false);
  }

  // The 3rd propagation pass allows adjust annotated BB weights that are
  // obviously wrong.
  Changed = true;
  while (Changed && I++ < SampleProfileMaxPropagateIterations) {
    Changed = propagateThroughEdges(F, true);
  }
}

/// Generate branch weight metadata for all branches in \p F.
///
/// Branch weights are computed out of instruction samples using a
/// propagation heuristic. Propagation proceeds in 3 phases:
///
/// 1- Assignment of block weights. All the basic blocks in the function
///    are initial assigned the same weight as their most frequently
///    executed instruction.
///
/// 2- Creation of equivalence classes. Since samples may be missing from
///    blocks, we can fill in the gaps by setting the weights of all the
///    blocks in the same equivalence class to the same weight. To compute
///    the concept of equivalence, we use dominance and loop information.
///    Two blocks B1 and B2 are in the same equivalence class if B1
///    dominates B2, B2 post-dominates B1 and both are in the same loop.
///
/// 3- Propagation of block weights into edges. This uses a simple
///    propagation heuristic. The following rules are applied to every
///    block BB in the CFG:
///
///    - If BB has a single predecessor/successor, then the weight
///      of that edge is the weight of the block.
///
///    - If all the edges are known except one, and the weight of the
///      block is already known, the weight of the unknown edge will
///      be the weight of the block minus the sum of all the known
///      edges. If the sum of all the known edges is larger than BB's weight,
///      we set the unknown edge weight to zero.
///
///    - If there is a self-referential edge, and the weight of the block is
///      known, the weight for that edge is set to the weight of the block
///      minus the weight of the other incoming edges to that block (if
///      known).
///
/// Since this propagation is not guaranteed to finalize for every CFG, we
/// only allow it to proceed for a limited number of iterations (controlled
/// by -sample-profile-max-propagate-iterations).
///
/// FIXME: Try to replace this propagation heuristic with a scheme
/// that is guaranteed to finalize. A work-list approach similar to
/// the standard value propagation algorithm used by SSA-CCP might
/// work here.
///
/// \param F The function to query.
///
/// \returns true if \p F was modified. Returns false, otherwise.
bool SampleProfileLoaderBaseImpl::computeAndPropagateWeights(
    Function &F, const DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
  bool Changed = (InlinedGUIDs.size() != 0);

  // Compute basic block weights.
  Changed |= computeBlockWeights(F);

  if (Changed) {
    // Add an entry count to the function using the samples gathered at the
    // function entry.
    // Sets the GUIDs that are inlined in the profiled binary. This is used
    // for ThinLink to make correct liveness analysis, and also make the IR
    // match the profiled binary before annotation.
    F.setEntryCount(
        ProfileCount(Samples->getHeadSamples() + 1, Function::PCT_Real),
        &InlinedGUIDs);

    // Compute dominance and loop info needed for propagation.
    computeDominanceAndLoopInfo(F);

    // Find equivalence classes.
    findEquivalenceClasses(F);

    // Propagate weights to all edges.
    propagateWeights(F);
  }

  return Changed;
}

void SampleProfileLoaderBaseImpl::emitCoverageRemarks(Function &F) {
  // If coverage checking was requested, compute it now.
  if (SampleProfileRecordCoverage) {
    unsigned Used = CoverageTracker.countUsedRecords(Samples, PSI);
    unsigned Total = CoverageTracker.countBodyRecords(Samples, PSI);
    unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
    if (Coverage < SampleProfileRecordCoverage) {
      F.getContext().diagnose(DiagnosticInfoSampleProfile(
          F.getSubprogram()->getFilename(), getFunctionLoc(F),
          Twine(Used) + " of " + Twine(Total) + " available profile records (" +
              Twine(Coverage) + "%) were applied",
          DS_Warning));
    }
  }

  if (SampleProfileSampleCoverage) {
    uint64_t Used = CoverageTracker.getTotalUsedSamples();
    uint64_t Total = CoverageTracker.countBodySamples(Samples, PSI);
    unsigned Coverage = CoverageTracker.computeCoverage(Used, Total);
    if (Coverage < SampleProfileSampleCoverage) {
      F.getContext().diagnose(DiagnosticInfoSampleProfile(
          F.getSubprogram()->getFilename(), getFunctionLoc(F),
          Twine(Used) + " of " + Twine(Total) + " available profile samples (" +
              Twine(Coverage) + "%) were applied",
          DS_Warning));
    }
  }
}

// Generate MD_prof metadata for every branch instruction using the
// edge weights computed during propagation.
void SampleProfileLoader::generateMDProfMetadata(Function &F) {
  // Generate MD_prof metadata for every branch instruction using the
  // edge weights computed during propagation.
  LLVM_DEBUG(dbgs() << "\nPropagation complete. Setting branch weights\n");
  LLVMContext &Ctx = F.getContext();
  MDBuilder MDB(Ctx);
  for (auto &BI : F) {
    BasicBlock *BB = &BI;

    if (BlockWeights[BB]) {
      for (auto &I : BB->getInstList()) {
        if (!isa<CallInst>(I) && !isa<InvokeInst>(I))
          continue;
        if (!cast<CallBase>(I).getCalledFunction()) {
          const DebugLoc &DLoc = I.getDebugLoc();
          if (!DLoc)
            continue;
          const DILocation *DIL = DLoc;
          const FunctionSamples *FS = findFunctionSamples(I);
          if (!FS)
            continue;
          auto CallSite = FunctionSamples::getCallSiteIdentifier(DIL);
          auto T = FS->findCallTargetMapAt(CallSite);
          if (!T || T.get().empty())
            continue;
          // Prorate the callsite counts to reflect what is already done to the
          // callsite, such as ICP or calliste cloning.
          if (FunctionSamples::ProfileIsProbeBased) {
            if (Optional<PseudoProbe> Probe = extractProbe(I)) {
              if (Probe->Factor < 1)
                T = SampleRecord::adjustCallTargets(T.get(), Probe->Factor);
            }
          }
          SmallVector<InstrProfValueData, 2> SortedCallTargets =
              GetSortedValueDataFromCallTargets(T.get());
          uint64_t Sum;
          findIndirectCallFunctionSamples(I, Sum);
          annotateValueSite(*I.getParent()->getParent()->getParent(), I,
                            SortedCallTargets, Sum, IPVK_IndirectCallTarget,
                            SortedCallTargets.size());
        } else if (!isa<IntrinsicInst>(&I)) {
          I.setMetadata(LLVMContext::MD_prof,
                        MDB.createBranchWeights(
                            {static_cast<uint32_t>(BlockWeights[BB])}));
        }
      }
    }
    Instruction *TI = BB->getTerminator();
    if (TI->getNumSuccessors() == 1)
      continue;
    if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
      continue;

    DebugLoc BranchLoc = TI->getDebugLoc();
    LLVM_DEBUG(dbgs() << "\nGetting weights for branch at line "
                      << ((BranchLoc) ? Twine(BranchLoc.getLine())
                                      : Twine("<UNKNOWN LOCATION>"))
                      << ".\n");
    SmallVector<uint32_t, 4> Weights;
    uint32_t MaxWeight = 0;
    Instruction *MaxDestInst;
    for (unsigned I = 0; I < TI->getNumSuccessors(); ++I) {
      BasicBlock *Succ = TI->getSuccessor(I);
      Edge E = std::make_pair(BB, Succ);
      uint64_t Weight = EdgeWeights[E];
      LLVM_DEBUG(dbgs() << "\t"; printEdgeWeight(dbgs(), E));
      // Use uint32_t saturated arithmetic to adjust the incoming weights,
      // if needed. Sample counts in profiles are 64-bit unsigned values,
      // but internally branch weights are expressed as 32-bit values.
      if (Weight > std::numeric_limits<uint32_t>::max()) {
        LLVM_DEBUG(dbgs() << " (saturated due to uint32_t overflow)");
        Weight = std::numeric_limits<uint32_t>::max();
      }
      // Weight is added by one to avoid propagation errors introduced by
      // 0 weights.
      Weights.push_back(static_cast<uint32_t>(Weight + 1));
      if (Weight != 0) {
        if (Weight > MaxWeight) {
          MaxWeight = Weight;
          MaxDestInst = Succ->getFirstNonPHIOrDbgOrLifetime();
        }
      }
    }

    uint64_t TempWeight;
    // Only set weights if there is at least one non-zero weight.
    // In any other case, let the analyzer set weights.
    // Do not set weights if the weights are present. In ThinLTO, the profile
    // annotation is done twice. If the first annotation already set the
    // weights, the second pass does not need to set it.
    if (MaxWeight > 0 && !TI->extractProfTotalWeight(TempWeight)) {
      LLVM_DEBUG(dbgs() << "SUCCESS. Found non-zero weights.\n");
      TI->setMetadata(LLVMContext::MD_prof,
                      MDB.createBranchWeights(Weights));
      ORE->emit([&]() {
        return OptimizationRemark(DEBUG_TYPE, "PopularDest", MaxDestInst)
               << "most popular destination for conditional branches at "
               << ore::NV("CondBranchesLoc", BranchLoc);
      });
    } else {
      LLVM_DEBUG(dbgs() << "SKIPPED. All branch weights are zero.\n");
    }
  }
}

/// Get the line number for the function header.
///
/// This looks up function \p F in the current compilation unit and
/// retrieves the line number where the function is defined. This is
/// line 0 for all the samples read from the profile file. Every line
/// number is relative to this line.
///
/// \param F  Function object to query.
///
/// \returns the line number where \p F is defined. If it returns 0,
///          it means that there is no debug information available for \p F.
unsigned SampleProfileLoaderBaseImpl::getFunctionLoc(Function &F) {
  if (DISubprogram *S = F.getSubprogram())
    return S->getLine();

  if (NoWarnSampleUnused)
    return 0;

  // If the start of \p F is missing, emit a diagnostic to inform the user
  // about the missed opportunity.
  F.getContext().diagnose(DiagnosticInfoSampleProfile(
      "No debug information found in function " + F.getName() +
          ": Function profile not used",
      DS_Warning));
  return 0;
}

void SampleProfileLoaderBaseImpl::computeDominanceAndLoopInfo(Function &F) {
  DT.reset(new DominatorTree);
  DT->recalculate(F);

  PDT.reset(new PostDominatorTree(F));

  LI.reset(new LoopInfo);
  LI->analyze(*DT);
}

/// Once all the branch weights are computed, we emit the MD_prof
/// metadata on BB using the computed values for each of its branches.
///
/// \param F The function to query.
///
/// \returns true if \p F was modified. Returns false, otherwise.
bool SampleProfileLoader::emitAnnotations(Function &F) {
  bool Changed = false;

  if (FunctionSamples::ProfileIsProbeBased) {
    if (!ProbeManager->profileIsValid(F, *Samples)) {
      LLVM_DEBUG(
          dbgs() << "Profile is invalid due to CFG mismatch for Function "
                 << F.getName());
      ++NumMismatchedProfile;
      return false;
    }
    ++NumMatchedProfile;
  } else {
    if (getFunctionLoc(F) == 0)
      return false;

    LLVM_DEBUG(dbgs() << "Line number for the first instruction in "
                      << F.getName() << ": " << getFunctionLoc(F) << "\n");
  }

  DenseSet<GlobalValue::GUID> InlinedGUIDs;
  if (ProfileIsCS && CallsitePrioritizedInline)
    Changed |= inlineHotFunctionsWithPriority(F, InlinedGUIDs);
  else
    Changed |= inlineHotFunctions(F, InlinedGUIDs);

  Changed |= computeAndPropagateWeights(F, InlinedGUIDs);

  if (Changed)
    generateMDProfMetadata(F);

  emitCoverageRemarks(F);
  return Changed;
}

char SampleProfileLoaderLegacyPass::ID = 0;

INITIALIZE_PASS_BEGIN(SampleProfileLoaderLegacyPass, "sample-profile",
                      "Sample Profile loader", false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
INITIALIZE_PASS_END(SampleProfileLoaderLegacyPass, "sample-profile",
                    "Sample Profile loader", false, false)

// Add inlined profile call edges to the call graph.
void SampleProfileLoader::addCallGraphEdges(CallGraph &CG,
                                            const FunctionSamples &Samples) {
  Function *Caller = SymbolMap.lookup(Samples.getFuncName());
  if (!Caller || Caller->isDeclaration())
    return;

  // Skip non-inlined call edges which are not important since top down inlining
  // for non-CS profile is to get more precise profile matching, not to enable
  // more inlining.

  for (const auto &CallsiteSamples : Samples.getCallsiteSamples()) {
    for (const auto &InlinedSamples : CallsiteSamples.second) {
      Function *Callee = SymbolMap.lookup(InlinedSamples.first);
      if (Callee && !Callee->isDeclaration())
        CG[Caller]->addCalledFunction(nullptr, CG[Callee]);
      addCallGraphEdges(CG, InlinedSamples.second);
    }
  }
}

// Replace call graph edges with dynamic call edges from the profile.
void SampleProfileLoader::replaceCallGraphEdges(
    CallGraph &CG, StringMap<Function *> &SymbolMap) {
  // Remove static call edges from the call graph except for the ones from the
  // root which make the call graph connected.
  for (const auto &Node : CG)
    if (Node.second.get() != CG.getExternalCallingNode())
      Node.second->removeAllCalledFunctions();

  // Add profile call edges to the call graph.
  if (ProfileIsCS) {
    ContextTracker->addCallGraphEdges(CG, SymbolMap);
  } else {
    for (const auto &Samples : Reader->getProfiles())
      addCallGraphEdges(CG, Samples.second);
  }
}

std::vector<Function *>
SampleProfileLoader::buildFunctionOrder(Module &M, CallGraph *CG) {
  std::vector<Function *> FunctionOrderList;
  FunctionOrderList.reserve(M.size());

  if (!ProfileTopDownLoad || CG == nullptr) {
    if (ProfileMergeInlinee) {
      // Disable ProfileMergeInlinee if profile is not loaded in top down order,
      // because the profile for a function may be used for the profile
      // annotation of its outline copy before the profile merging of its
      // non-inlined inline instances, and that is not the way how
      // ProfileMergeInlinee is supposed to work.
      ProfileMergeInlinee = false;
    }

    for (Function &F : M)
      if (!F.isDeclaration() && F.hasFnAttribute("use-sample-profile"))
        FunctionOrderList.push_back(&F);
    return FunctionOrderList;
  }

  assert(&CG->getModule() == &M);

  // Add indirect call edges from profile to augment the static call graph.
  // Functions will be processed in a top-down order defined by the static call
  // graph. Adjusting the order by considering indirect call edges from the
  // profile (which don't exist in the static call graph) can enable the
  // inlining of indirect call targets by processing the caller before them.
  // TODO: enable this for non-CS profile and fix the counts returning logic to
  // have a full support for indirect calls.
  if (UseProfileIndirectCallEdges && ProfileIsCS) {
    for (auto &Entry : *CG) {
      const auto *F = Entry.first;
      if (!F || F->isDeclaration() || !F->hasFnAttribute("use-sample-profile"))
        continue;
      auto &AllContexts = ContextTracker->getAllContextSamplesFor(F->getName());
      if (AllContexts.empty())
        continue;

      for (const auto &BB : *F) {
        for (const auto &I : BB.getInstList()) {
          const auto *CB = dyn_cast<CallBase>(&I);
          if (!CB || !CB->isIndirectCall())
            continue;
          const DebugLoc &DLoc = I.getDebugLoc();
          if (!DLoc)
            continue;
          auto CallSite = FunctionSamples::getCallSiteIdentifier(DLoc);
          for (FunctionSamples *Samples : AllContexts) {
            if (auto CallTargets = Samples->findCallTargetMapAt(CallSite)) {
              for (const auto &Target : CallTargets.get()) {
                Function *Callee = SymbolMap.lookup(Target.first());
                if (Callee && !Callee->isDeclaration())
                  Entry.second->addCalledFunction(nullptr, (*CG)[Callee]);
              }
            }
          }
        }
      }
    }
  }

  // Compute a top-down order the profile which is used to sort functions in
  // one SCC later. The static processing order computed for an SCC may not
  // reflect the call contexts in the context-sensitive profile, thus may cause
  // potential inlining to be overlooked. The function order in one SCC is being
  // adjusted to a top-down order based on the profile to favor more inlining.
  DenseMap<Function *, uint64_t> ProfileOrderMap;
  if (UseProfileTopDownOrder ||
      (ProfileIsCS && !UseProfileTopDownOrder.getNumOccurrences())) {
    // Create a static call graph. The call edges are not important since they
    // will be replaced by dynamic edges from the profile.
    CallGraph ProfileCG(M);
    replaceCallGraphEdges(ProfileCG, SymbolMap);
    scc_iterator<CallGraph *> CGI = scc_begin(&ProfileCG);
    uint64_t I = 0;
    while (!CGI.isAtEnd()) {
      for (CallGraphNode *Node : *CGI) {
        if (auto *F = Node->getFunction())
          ProfileOrderMap[F] = ++I;
      }
      ++CGI;
    }
  }

  scc_iterator<CallGraph *> CGI = scc_begin(CG);
  while (!CGI.isAtEnd()) {
    uint64_t Start = FunctionOrderList.size();
    for (CallGraphNode *Node : *CGI) {
      auto *F = Node->getFunction();
      if (F && !F->isDeclaration() && F->hasFnAttribute("use-sample-profile"))
        FunctionOrderList.push_back(F);
    }

    // Sort nodes in SCC based on the profile top-down order.
    if (!ProfileOrderMap.empty()) {
      std::stable_sort(FunctionOrderList.begin() + Start,
                       FunctionOrderList.end(),
                       [&ProfileOrderMap](Function *Left, Function *Right) {
                         return ProfileOrderMap[Left] < ProfileOrderMap[Right];
                       });
    }

    ++CGI;
  }

  LLVM_DEBUG({
    dbgs() << "Function processing order:\n";
    for (auto F : reverse(FunctionOrderList)) {
      dbgs() << F->getName() << "\n";
    }
  });

  std::reverse(FunctionOrderList.begin(), FunctionOrderList.end());
  return FunctionOrderList;
}

bool SampleProfileLoader::doInitialization(Module &M,
                                           FunctionAnalysisManager *FAM) {
  auto &Ctx = M.getContext();

  auto ReaderOrErr =
      SampleProfileReader::create(Filename, Ctx, RemappingFilename);
  if (std::error_code EC = ReaderOrErr.getError()) {
    std::string Msg = "Could not open profile: " + EC.message();
    Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
    return false;
  }
  Reader = std::move(ReaderOrErr.get());
  Reader->setSkipFlatProf(LTOPhase == ThinOrFullLTOPhase::ThinLTOPostLink);
  Reader->collectFuncsFrom(M);
  if (std::error_code EC = Reader->read()) {
    std::string Msg = "profile reading failed: " + EC.message();
    Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
    return false;
  }

  PSL = Reader->getProfileSymbolList();

  // While profile-sample-accurate is on, ignore symbol list.
  ProfAccForSymsInList =
      ProfileAccurateForSymsInList && PSL && !ProfileSampleAccurate;
  if (ProfAccForSymsInList) {
    NamesInProfile.clear();
    if (auto NameTable = Reader->getNameTable())
      NamesInProfile.insert(NameTable->begin(), NameTable->end());
    CoverageTracker.setProfAccForSymsInList(true);
  }

  if (FAM && !ProfileInlineReplayFile.empty()) {
    ExternalInlineAdvisor = std::make_unique<ReplayInlineAdvisor>(
        M, *FAM, Ctx, /*OriginalAdvisor=*/nullptr, ProfileInlineReplayFile,
        /*EmitRemarks=*/false);
    if (!ExternalInlineAdvisor->areReplayRemarksLoaded())
      ExternalInlineAdvisor.reset();
  }

  // Apply tweaks if context-sensitive profile is available.
  if (Reader->profileIsCS()) {
    ProfileIsCS = true;
    FunctionSamples::ProfileIsCS = true;

    // Enable priority-base inliner and size inline by default for CSSPGO.
    if (!ProfileSizeInline.getNumOccurrences())
      ProfileSizeInline = true;
    if (!CallsitePrioritizedInline.getNumOccurrences())
      CallsitePrioritizedInline = true;

    // Tracker for profiles under different context
    ContextTracker =
        std::make_unique<SampleContextTracker>(Reader->getProfiles());
  }

  // Load pseudo probe descriptors for probe-based function samples.
  if (Reader->profileIsProbeBased()) {
    ProbeManager = std::make_unique<PseudoProbeManager>(M);
    if (!ProbeManager->moduleIsProbed(M)) {
      const char *Msg =
          "Pseudo-probe-based profile requires SampleProfileProbePass";
      Ctx.diagnose(DiagnosticInfoSampleProfile(Filename, Msg));
      return false;
    }
  }

  return true;
}

ModulePass *llvm::createSampleProfileLoaderPass() {
  return new SampleProfileLoaderLegacyPass();
}

ModulePass *llvm::createSampleProfileLoaderPass(StringRef Name) {
  return new SampleProfileLoaderLegacyPass(Name);
}

bool SampleProfileLoader::runOnModule(Module &M, ModuleAnalysisManager *AM,
                                      ProfileSummaryInfo *_PSI, CallGraph *CG) {
  GUIDToFuncNameMapper Mapper(M, *Reader, GUIDToFuncNameMap);

  PSI = _PSI;
  if (M.getProfileSummary(/* IsCS */ false) == nullptr) {
    M.setProfileSummary(Reader->getSummary().getMD(M.getContext()),
                        ProfileSummary::PSK_Sample);
    PSI->refresh();
  }
  // Compute the total number of samples collected in this profile.
  for (const auto &I : Reader->getProfiles())
    TotalCollectedSamples += I.second.getTotalSamples();

  auto Remapper = Reader->getRemapper();
  // Populate the symbol map.
  for (const auto &N_F : M.getValueSymbolTable()) {
    StringRef OrigName = N_F.getKey();
    Function *F = dyn_cast<Function>(N_F.getValue());
    if (F == nullptr)
      continue;
    SymbolMap[OrigName] = F;
    auto pos = OrigName.find('.');
    if (pos != StringRef::npos) {
      StringRef NewName = OrigName.substr(0, pos);
      auto r = SymbolMap.insert(std::make_pair(NewName, F));
      // Failiing to insert means there is already an entry in SymbolMap,
      // thus there are multiple functions that are mapped to the same
      // stripped name. In this case of name conflicting, set the value
      // to nullptr to avoid confusion.
      if (!r.second)
        r.first->second = nullptr;
      OrigName = NewName;
    }
    // Insert the remapped names into SymbolMap.
    if (Remapper) {
      if (auto MapName = Remapper->lookUpNameInProfile(OrigName)) {
        if (*MapName == OrigName)
          continue;
        SymbolMap.insert(std::make_pair(*MapName, F));
      }
    }
  }

  bool retval = false;
  for (auto F : buildFunctionOrder(M, CG)) {
    assert(!F->isDeclaration());
    clearFunctionData();
    retval |= runOnFunction(*F, AM);
  }

  // Account for cold calls not inlined....
  if (!ProfileIsCS)
    for (const std::pair<Function *, NotInlinedProfileInfo> &pair :
         notInlinedCallInfo)
      updateProfileCallee(pair.first, pair.second.entryCount);

  return retval;
}

bool SampleProfileLoaderLegacyPass::runOnModule(Module &M) {
  ACT = &getAnalysis<AssumptionCacheTracker>();
  TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
  TLIWP = &getAnalysis<TargetLibraryInfoWrapperPass>();
  ProfileSummaryInfo *PSI =
      &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
  return SampleLoader.runOnModule(M, nullptr, PSI, nullptr);
}

bool SampleProfileLoader::runOnFunction(Function &F, ModuleAnalysisManager *AM) {
  LLVM_DEBUG(dbgs() << "\n\nProcessing Function " << F.getName() << "\n");
  DILocation2SampleMap.clear();
  // By default the entry count is initialized to -1, which will be treated
  // conservatively by getEntryCount as the same as unknown (None). This is
  // to avoid newly added code to be treated as cold. If we have samples
  // this will be overwritten in emitAnnotations.
  uint64_t initialEntryCount = -1;

  ProfAccForSymsInList = ProfileAccurateForSymsInList && PSL;
  if (ProfileSampleAccurate || F.hasFnAttribute("profile-sample-accurate")) {
    // initialize all the function entry counts to 0. It means all the
    // functions without profile will be regarded as cold.
    initialEntryCount = 0;
    // profile-sample-accurate is a user assertion which has a higher precedence
    // than symbol list. When profile-sample-accurate is on, ignore symbol list.
    ProfAccForSymsInList = false;
  }
  CoverageTracker.setProfAccForSymsInList(ProfAccForSymsInList);

  // PSL -- profile symbol list include all the symbols in sampled binary.
  // If ProfileAccurateForSymsInList is enabled, PSL is used to treat
  // old functions without samples being cold, without having to worry
  // about new and hot functions being mistakenly treated as cold.
  if (ProfAccForSymsInList) {
    // Initialize the entry count to 0 for functions in the list.
    if (PSL->contains(F.getName()))
      initialEntryCount = 0;

    // Function in the symbol list but without sample will be regarded as
    // cold. To minimize the potential negative performance impact it could
    // have, we want to be a little conservative here saying if a function
    // shows up in the profile, no matter as outline function, inline instance
    // or call targets, treat the function as not being cold. This will handle
    // the cases such as most callsites of a function are inlined in sampled
    // binary but not inlined in current build (because of source code drift,
    // imprecise debug information, or the callsites are all cold individually
    // but not cold accumulatively...), so the outline function showing up as
    // cold in sampled binary will actually not be cold after current build.
    StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
    if (NamesInProfile.count(CanonName))
      initialEntryCount = -1;
  }

  // Initialize entry count when the function has no existing entry
  // count value.
  if (!F.getEntryCount().hasValue())
    F.setEntryCount(ProfileCount(initialEntryCount, Function::PCT_Real));
  std::unique_ptr<OptimizationRemarkEmitter> OwnedORE;
  if (AM) {
    auto &FAM =
        AM->getResult<FunctionAnalysisManagerModuleProxy>(*F.getParent())
            .getManager();
    ORE = &FAM.getResult<OptimizationRemarkEmitterAnalysis>(F);
  } else {
    OwnedORE = std::make_unique<OptimizationRemarkEmitter>(&F);
    ORE = OwnedORE.get();
  }

  if (ProfileIsCS)
    Samples = ContextTracker->getBaseSamplesFor(F);
  else
    Samples = Reader->getSamplesFor(F);

  if (Samples && !Samples->empty())
    return emitAnnotations(F);
  return false;
}

PreservedAnalyses SampleProfileLoaderPass::run(Module &M,
                                               ModuleAnalysisManager &AM) {
  FunctionAnalysisManager &FAM =
      AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();

  auto GetAssumptionCache = [&](Function &F) -> AssumptionCache & {
    return FAM.getResult<AssumptionAnalysis>(F);
  };
  auto GetTTI = [&](Function &F) -> TargetTransformInfo & {
    return FAM.getResult<TargetIRAnalysis>(F);
  };
  auto GetTLI = [&](Function &F) -> const TargetLibraryInfo & {
    return FAM.getResult<TargetLibraryAnalysis>(F);
  };

  SampleProfileLoader SampleLoader(
      ProfileFileName.empty() ? SampleProfileFile : ProfileFileName,
      ProfileRemappingFileName.empty() ? SampleProfileRemappingFile
                                       : ProfileRemappingFileName,
      LTOPhase, GetAssumptionCache, GetTTI, GetTLI);

  if (!SampleLoader.doInitialization(M, &FAM))
    return PreservedAnalyses::all();

  ProfileSummaryInfo *PSI = &AM.getResult<ProfileSummaryAnalysis>(M);
  CallGraph &CG = AM.getResult<CallGraphAnalysis>(M);
  if (!SampleLoader.runOnModule(M, &AM, PSI, &CG))
    return PreservedAnalyses::all();

  return PreservedAnalyses::none();
}