tools/llvm-profgen/ProfileGenerator.cpp

//===-- ProfileGenerator.cpp - Profile Generator  ---------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "ProfileGenerator.h"
#include "ErrorHandling.h"
#include "ProfiledBinary.h"
#include "llvm/DebugInfo/Symbolize/SymbolizableModule.h"
#include "llvm/ProfileData/ProfileCommon.h"
#include <algorithm>
#include <float.h>
#include <unordered_set>

cl::opt<std::string> OutputFilename("output", cl::value_desc("output"),
                                    cl::Required,
                                    cl::desc("Output profile file"));
static cl::alias OutputA("o", cl::desc("Alias for --output"),
                         cl::aliasopt(OutputFilename));

static cl::opt<SampleProfileFormat> OutputFormat(
    "format", cl::desc("Format of output profile"), cl::init(SPF_Ext_Binary),
    cl::values(
        clEnumValN(SPF_Binary, "binary", "Binary encoding (default)"),
        clEnumValN(SPF_Compact_Binary, "compbinary", "Compact binary encoding"),
        clEnumValN(SPF_Ext_Binary, "extbinary", "Extensible binary encoding"),
        clEnumValN(SPF_Text, "text", "Text encoding"),
        clEnumValN(SPF_GCC, "gcc",
                   "GCC encoding (only meaningful for -sample)")));

cl::opt<bool> UseMD5(
    "use-md5", cl::init(false), cl::Hidden,
    cl::desc("Use md5 to represent function names in the output profile (only "
             "meaningful for -extbinary)"));

static cl::opt<bool> PopulateProfileSymbolList(
    "populate-profile-symbol-list", cl::init(false), cl::Hidden,
    cl::desc("Populate profile symbol list (only meaningful for -extbinary)"));

static cl::opt<bool> FillZeroForAllFuncs(
    "fill-zero-for-all-funcs", cl::init(false), cl::Hidden,
    cl::desc("Attribute all functions' range with zero count "
             "even it's not hit by any samples."));

static cl::opt<int32_t, true> RecursionCompression(
    "compress-recursion",
    cl::desc("Compressing recursion by deduplicating adjacent frame "
             "sequences up to the specified size. -1 means no size limit."),
    cl::Hidden,
    cl::location(llvm::sampleprof::CSProfileGenerator::MaxCompressionSize));

static cl::opt<bool>
    TrimColdProfile("trim-cold-profile", cl::init(false), cl::ZeroOrMore,
                    cl::desc("If the total count of the profile is smaller "
                             "than threshold, it will be trimmed."));

static cl::opt<bool> CSProfMergeColdContext(
    "csprof-merge-cold-context", cl::init(true), cl::ZeroOrMore,
    cl::desc("If the total count of context profile is smaller than "
             "the threshold, it will be merged into context-less base "
             "profile."));

static cl::opt<uint32_t> CSProfMaxColdContextDepth(
    "csprof-max-cold-context-depth", cl::init(1), cl::ZeroOrMore,
    cl::desc("Keep the last K contexts while merging cold profile. 1 means the "
             "context-less base profile"));

static cl::opt<int, true> CSProfMaxContextDepth(
    "csprof-max-context-depth", cl::ZeroOrMore,
    cl::desc("Keep the last K contexts while merging profile. -1 means no "
             "depth limit."),
    cl::location(llvm::sampleprof::CSProfileGenerator::MaxContextDepth));

static cl::opt<double> HotFunctionDensityThreshold(
    "hot-function-density-threshold", llvm::cl::init(1000),
    llvm::cl::desc(
        "specify density threshold for hot functions (default: 1000)"),
    llvm::cl::Optional);
static cl::opt<bool> ShowDensity("show-density", llvm::cl::init(false),
                                 llvm::cl::desc("show profile density details"),
                                 llvm::cl::Optional);

static cl::opt<bool> UpdateTotalSamples(
    "update-total-samples", llvm::cl::init(false),
    llvm::cl::desc(
        "Update total samples by accumulating all its body samples."),
    llvm::cl::Optional);

extern cl::opt<int> ProfileSummaryCutoffHot;

static cl::opt<bool> GenCSNestedProfile(
    "gen-cs-nested-profile", cl::Hidden, cl::init(true),
    cl::desc("Generate nested function profiles for CSSPGO"));

using namespace llvm;
using namespace sampleprof;

namespace llvm {
namespace sampleprof {

// Initialize the MaxCompressionSize to -1 which means no size limit
int32_t CSProfileGenerator::MaxCompressionSize = -1;

int CSProfileGenerator::MaxContextDepth = -1;

bool ProfileGeneratorBase::UseFSDiscriminator = false;

std::unique_ptr<ProfileGeneratorBase>
ProfileGeneratorBase::create(ProfiledBinary *Binary,
                             const ContextSampleCounterMap &SampleCounters,
                             bool ProfileIsCSFlat) {
  std::unique_ptr<ProfileGeneratorBase> Generator;
  if (ProfileIsCSFlat) {
    if (Binary->useFSDiscriminator())
      exitWithError("FS discriminator is not supported in CS profile.");
    Generator.reset(new CSProfileGenerator(Binary, SampleCounters));
  } else {
    Generator.reset(new ProfileGenerator(Binary, SampleCounters));
  }
  ProfileGeneratorBase::UseFSDiscriminator = Binary->useFSDiscriminator();
  FunctionSamples::ProfileIsFS = Binary->useFSDiscriminator();

  return Generator;
}

void ProfileGeneratorBase::write(std::unique_ptr<SampleProfileWriter> Writer,
                                 SampleProfileMap &ProfileMap) {
  // Populate profile symbol list if extended binary format is used.
  ProfileSymbolList SymbolList;

  if (PopulateProfileSymbolList && OutputFormat == SPF_Ext_Binary) {
    Binary->populateSymbolListFromDWARF(SymbolList);
    Writer->setProfileSymbolList(&SymbolList);
  }

  if (std::error_code EC = Writer->write(ProfileMap))
    exitWithError(std::move(EC));
}

void ProfileGeneratorBase::write() {
  auto WriterOrErr = SampleProfileWriter::create(OutputFilename, OutputFormat);
  if (std::error_code EC = WriterOrErr.getError())
    exitWithError(EC, OutputFilename);

  if (UseMD5) {
    if (OutputFormat != SPF_Ext_Binary)
      WithColor::warning() << "-use-md5 is ignored. Specify "
                              "--format=extbinary to enable it\n";
    else
      WriterOrErr.get()->setUseMD5();
  }

  write(std::move(WriterOrErr.get()), ProfileMap);
}

void ProfileGeneratorBase::showDensitySuggestion(double Density) {
  if (Density == 0.0)
    WithColor::warning() << "The --profile-summary-cutoff-hot option may be "
                            "set too low. Please check your command.\n";
  else if (Density < HotFunctionDensityThreshold)
    WithColor::warning()
        << "AutoFDO is estimated to optimize better with "
        << format("%.1f", HotFunctionDensityThreshold / Density)
        << "x more samples. Please consider increasing sampling rate or "
           "profiling for longer duration to get more samples.\n";

  if (ShowDensity)
    outs() << "Minimum profile density for hot functions with top "
           << format("%.2f",
                     static_cast<double>(ProfileSummaryCutoffHot.getValue()) /
                         10000)
           << "% total samples: " << format("%.1f", Density) << "\n";
}

double ProfileGeneratorBase::calculateDensity(const SampleProfileMap &Profiles,
                                              uint64_t HotCntThreshold) {
  double Density = DBL_MAX;
  std::vector<const FunctionSamples *> HotFuncs;
  for (auto &I : Profiles) {
    auto &FuncSamples = I.second;
    if (FuncSamples.getTotalSamples() < HotCntThreshold)
      continue;
    HotFuncs.emplace_back(&FuncSamples);
  }

  for (auto *FuncSamples : HotFuncs) {
    auto *Func = Binary->getBinaryFunction(FuncSamples->getName());
    if (!Func)
      continue;
    uint64_t FuncSize = Func->getFuncSize();
    if (FuncSize == 0)
      continue;
    Density =
        std::min(Density, static_cast<double>(FuncSamples->getTotalSamples()) /
                              FuncSize);
  }

  return Density == DBL_MAX ? 0.0 : Density;
}

void ProfileGeneratorBase::findDisjointRanges(RangeSample &DisjointRanges,
                                              const RangeSample &Ranges) {

  /*
  Regions may overlap with each other. Using the boundary info, find all
  disjoint ranges and their sample count. BoundaryPoint contains the count
  multiple samples begin/end at this points.

  |<--100-->|           Sample1
  |<------200------>|   Sample2
  A         B       C

  In the example above,
  Sample1 begins at A, ends at B, its value is 100.
  Sample2 beings at A, ends at C, its value is 200.
  For A, BeginCount is the sum of sample begins at A, which is 300 and no
  samples ends at A, so EndCount is 0.
  Then boundary points A, B, and C with begin/end counts are:
  A: (300, 0)
  B: (0, 100)
  C: (0, 200)
  */
  struct BoundaryPoint {
    // Sum of sample counts beginning at this point
    uint64_t BeginCount = UINT64_MAX;
    // Sum of sample counts ending at this point
    uint64_t EndCount = UINT64_MAX;
    // Is the begin point of a zero range.
    bool IsZeroRangeBegin = false;
    // Is the end point of a zero range.
    bool IsZeroRangeEnd = false;

    void addBeginCount(uint64_t Count) {
      if (BeginCount == UINT64_MAX)
        BeginCount = 0;
      BeginCount += Count;
    }

    void addEndCount(uint64_t Count) {
      if (EndCount == UINT64_MAX)
        EndCount = 0;
      EndCount += Count;
    }
  };

  /*
  For the above example. With boundary points, follwing logic finds two
  disjoint region of

  [A,B]:   300
  [B+1,C]: 200

  If there is a boundary point that both begin and end, the point itself
  becomes a separate disjoint region. For example, if we have original
  ranges of

  |<--- 100 --->|
                |<--- 200 --->|
  A             B             C

  there are three boundary points with their begin/end counts of

  A: (100, 0)
  B: (200, 100)
  C: (0, 200)

  the disjoint ranges would be

  [A, B-1]: 100
  [B, B]:   300
  [B+1, C]: 200.

  Example for zero value range:

    |<--- 100 --->|
                       |<--- 200 --->|
  |<---------------  0 ----------------->|
  A  B            C    D             E   F

  [A, B-1]  : 0
  [B, C]    : 100
  [C+1, D-1]: 0
  [D, E]    : 200
  [E+1, F]  : 0
  */
  std::map<uint64_t, BoundaryPoint> Boundaries;

  for (const auto &Item : Ranges) {
    assert(Item.first.first <= Item.first.second &&
           "Invalid instruction range");
    auto &BeginPoint = Boundaries[Item.first.first];
    auto &EndPoint = Boundaries[Item.first.second];
    uint64_t Count = Item.second;

    BeginPoint.addBeginCount(Count);
    EndPoint.addEndCount(Count);
    if (Count == 0) {
      BeginPoint.IsZeroRangeBegin = true;
      EndPoint.IsZeroRangeEnd = true;
    }
  }

  // Use UINT64_MAX to indicate there is no existing range between BeginAddress
  // and the next valid address
  uint64_t BeginAddress = UINT64_MAX;
  int ZeroRangeDepth = 0;
  uint64_t Count = 0;
  for (const auto &Item : Boundaries) {
    uint64_t Address = Item.first;
    const BoundaryPoint &Point = Item.second;
    if (Point.BeginCount != UINT64_MAX) {
      if (BeginAddress != UINT64_MAX)
        DisjointRanges[{BeginAddress, Address - 1}] = Count;
      Count += Point.BeginCount;
      BeginAddress = Address;
      ZeroRangeDepth += Point.IsZeroRangeBegin;
    }
    if (Point.EndCount != UINT64_MAX) {
      assert((BeginAddress != UINT64_MAX) &&
             "First boundary point cannot be 'end' point");
      DisjointRanges[{BeginAddress, Address}] = Count;
      assert(Count >= Point.EndCount && "Mismatched live ranges");
      Count -= Point.EndCount;
      BeginAddress = Address + 1;
      ZeroRangeDepth -= Point.IsZeroRangeEnd;
      // If the remaining count is zero and it's no longer in a zero range, this
      // means we consume all the ranges before, thus mark BeginAddress as
      // UINT64_MAX. e.g. supposing we have two non-overlapping ranges:
      //  [<---- 10 ---->]
      //                       [<---- 20 ---->]
      //   A             B     C              D
      // The BeginAddress(B+1) will reset to invalid(UINT64_MAX), so we won't
      // have the [B+1, C-1] zero range.
      if (Count == 0 && ZeroRangeDepth == 0)
        BeginAddress = UINT64_MAX;
    }
  }
}

void ProfileGeneratorBase::updateBodySamplesforFunctionProfile(
    FunctionSamples &FunctionProfile, const SampleContextFrame &LeafLoc,
    uint64_t Count) {
  // Use the maximum count of samples with same line location
  uint32_t Discriminator = getBaseDiscriminator(LeafLoc.Location.Discriminator);

  // Use duplication factor to compensated for loop unroll/vectorization.
  // Note that this is only needed when we're taking MAX of the counts at
  // the location instead of SUM.
  Count *= getDuplicationFactor(LeafLoc.Location.Discriminator);

  ErrorOr<uint64_t> R =
      FunctionProfile.findSamplesAt(LeafLoc.Location.LineOffset, Discriminator);

  uint64_t PreviousCount = R ? R.get() : 0;
  if (PreviousCount <= Count) {
    FunctionProfile.addBodySamples(LeafLoc.Location.LineOffset, Discriminator,
                                   Count - PreviousCount);
  }
}

void ProfileGeneratorBase::updateTotalSamples() {
  if (!UpdateTotalSamples)
    return;

  for (auto &Item : ProfileMap) {
    FunctionSamples &FunctionProfile = Item.second;
    FunctionProfile.updateTotalSamples();
  }
}

void ProfileGeneratorBase::collectProfiledFunctions() {
  std::unordered_set<const BinaryFunction *> ProfiledFunctions;
  // Go through all the stacks, ranges and branches in sample counters, use the
  // start of the range to look up the function it belongs and record the
  // function.
  for (const auto &CI : SampleCounters) {
    if (const auto *CtxKey = dyn_cast<AddrBasedCtxKey>(CI.first.getPtr())) {
      for (auto Addr : CtxKey->Context) {
        if (FuncRange *FRange = Binary->findFuncRangeForOffset(
                Binary->virtualAddrToOffset(Addr)))
          ProfiledFunctions.insert(FRange->Func);
      }
    }

    for (auto Item : CI.second.RangeCounter) {
      uint64_t StartOffset = Item.first.first;
      if (FuncRange *FRange = Binary->findFuncRangeForOffset(StartOffset))
        ProfiledFunctions.insert(FRange->Func);
    }

    for (auto Item : CI.second.BranchCounter) {
      uint64_t SourceOffset = Item.first.first;
      uint64_t TargetOffset = Item.first.first;
      if (FuncRange *FRange = Binary->findFuncRangeForOffset(SourceOffset))
        ProfiledFunctions.insert(FRange->Func);
      if (FuncRange *FRange = Binary->findFuncRangeForOffset(TargetOffset))
        ProfiledFunctions.insert(FRange->Func);
    }
  }

  Binary->setProfiledFunctions(ProfiledFunctions);
}

FunctionSamples &
ProfileGenerator::getTopLevelFunctionProfile(StringRef FuncName) {
  SampleContext Context(FuncName);
  auto Ret = ProfileMap.emplace(Context, FunctionSamples());
  if (Ret.second) {
    FunctionSamples &FProfile = Ret.first->second;
    FProfile.setContext(Context);
  }
  return Ret.first->second;
}

void ProfileGenerator::generateProfile() {
  collectProfiledFunctions();
  if (Binary->usePseudoProbes()) {
    generateProbeBasedProfile();
  } else {
    generateLineNumBasedProfile();
  }
  postProcessProfiles();
}

void ProfileGenerator::postProcessProfiles() {
  computeSummaryAndThreshold();
  trimColdProfiles(ProfileMap, ColdCountThreshold);
  calculateAndShowDensity(ProfileMap);
}

void ProfileGenerator::trimColdProfiles(const SampleProfileMap &Profiles,
                                        uint64_t ColdCntThreshold) {
  if (!TrimColdProfile)
    return;

  // Move cold profiles into a tmp container.
  std::vector<SampleContext> ColdProfiles;
  for (const auto &I : ProfileMap) {
    if (I.second.getTotalSamples() < ColdCntThreshold)
      ColdProfiles.emplace_back(I.first);
  }

  // Remove the cold profile from ProfileMap.
  for (const auto &I : ColdProfiles)
    ProfileMap.erase(I);
}

void ProfileGenerator::generateLineNumBasedProfile() {
  assert(SampleCounters.size() == 1 &&
         "Must have one entry for profile generation.");
  const SampleCounter &SC = SampleCounters.begin()->second;
  // Fill in function body samples
  populateBodySamplesForAllFunctions(SC.RangeCounter);
  // Fill in boundary sample counts as well as call site samples for calls
  populateBoundarySamplesForAllFunctions(SC.BranchCounter);

  updateTotalSamples();
}

void ProfileGenerator::generateProbeBasedProfile() {
  assert(SampleCounters.size() == 1 &&
         "Must have one entry for profile generation.");
  Binary->decodePseudoProbe();
  // Enable pseudo probe functionalities in SampleProf
  FunctionSamples::ProfileIsProbeBased = true;
  const SampleCounter &SC = SampleCounters.begin()->second;
  // Fill in function body samples
  populateBodySamplesWithProbesForAllFunctions(SC.RangeCounter);
  // Fill in boundary sample counts as well as call site samples for calls
  populateBoundarySamplesWithProbesForAllFunctions(SC.BranchCounter);

  updateTotalSamples();
}

void ProfileGenerator::populateBodySamplesWithProbesForAllFunctions(
    const RangeSample &RangeCounter) {
  ProbeCounterMap ProbeCounter;
  // preprocessRangeCounter returns disjoint ranges, so no longer to redo it
  // inside extractProbesFromRange.
  extractProbesFromRange(preprocessRangeCounter(RangeCounter), ProbeCounter,
                         false);

  for (const auto &PI : ProbeCounter) {
    const MCDecodedPseudoProbe *Probe = PI.first;
    uint64_t Count = PI.second;
    SampleContextFrameVector FrameVec;
    Binary->getInlineContextForProbe(Probe, FrameVec, true);
    FunctionSamples &FunctionProfile =
        getLeafProfileAndAddTotalSamples(FrameVec, Count);
    FunctionProfile.addBodySamplesForProbe(Probe->getIndex(), Count);
    if (Probe->isEntry())
      FunctionProfile.addHeadSamples(Count);
  }
}

void ProfileGenerator::populateBoundarySamplesWithProbesForAllFunctions(
    const BranchSample &BranchCounters) {
  for (const auto &Entry : BranchCounters) {
    uint64_t SourceOffset = Entry.first.first;
    uint64_t TargetOffset = Entry.first.second;
    uint64_t Count = Entry.second;
    assert(Count != 0 && "Unexpected zero weight branch");

    StringRef CalleeName = getCalleeNameForOffset(TargetOffset);
    if (CalleeName.size() == 0)
      continue;

    uint64_t SourceAddress = Binary->offsetToVirtualAddr(SourceOffset);
    const MCDecodedPseudoProbe *CallProbe =
        Binary->getCallProbeForAddr(SourceAddress);
    if (CallProbe == nullptr)
      continue;

    // Record called target sample and its count.
    SampleContextFrameVector FrameVec;
    Binary->getInlineContextForProbe(CallProbe, FrameVec, true);

    if (!FrameVec.empty()) {
      FunctionSamples &FunctionProfile =
          getLeafProfileAndAddTotalSamples(FrameVec, 0);
      FunctionProfile.addCalledTargetSamples(
          FrameVec.back().Location.LineOffset, 0, CalleeName, Count);
    }
  }
}

FunctionSamples &ProfileGenerator::getLeafProfileAndAddTotalSamples(
    const SampleContextFrameVector &FrameVec, uint64_t Count) {
  // Get top level profile
  FunctionSamples *FunctionProfile =
      &getTopLevelFunctionProfile(FrameVec[0].FuncName);
  FunctionProfile->addTotalSamples(Count);
  if (Binary->usePseudoProbes()) {
    const auto *FuncDesc = Binary->getFuncDescForGUID(
        Function::getGUID(FunctionProfile->getName()));
    FunctionProfile->setFunctionHash(FuncDesc->FuncHash);
  }

  for (size_t I = 1; I < FrameVec.size(); I++) {
    LineLocation Callsite(
        FrameVec[I - 1].Location.LineOffset,
        getBaseDiscriminator(FrameVec[I - 1].Location.Discriminator));
    FunctionSamplesMap &SamplesMap =
        FunctionProfile->functionSamplesAt(Callsite);
    auto Ret =
        SamplesMap.emplace(FrameVec[I].FuncName.str(), FunctionSamples());
    if (Ret.second) {
      SampleContext Context(FrameVec[I].FuncName);
      Ret.first->second.setContext(Context);
    }
    FunctionProfile = &Ret.first->second;
    FunctionProfile->addTotalSamples(Count);
    if (Binary->usePseudoProbes()) {
      const auto *FuncDesc = Binary->getFuncDescForGUID(
          Function::getGUID(FunctionProfile->getName()));
      FunctionProfile->setFunctionHash(FuncDesc->FuncHash);
    }
  }

  return *FunctionProfile;
}

RangeSample
ProfileGenerator::preprocessRangeCounter(const RangeSample &RangeCounter) {
  RangeSample Ranges(RangeCounter.begin(), RangeCounter.end());
  if (FillZeroForAllFuncs) {
    for (auto &FuncI : Binary->getAllBinaryFunctions()) {
      for (auto &R : FuncI.second.Ranges) {
        Ranges[{R.first, R.second - 1}] += 0;
      }
    }
  } else {
    // For each range, we search for all ranges of the function it belongs to
    // and initialize it with zero count, so it remains zero if doesn't hit any
    // samples. This is to be consistent with compiler that interpret zero count
    // as unexecuted(cold).
    for (const auto &I : RangeCounter) {
      uint64_t StartOffset = I.first.first;
      for (const auto &Range : Binary->getRangesForOffset(StartOffset))
        Ranges[{Range.first, Range.second - 1}] += 0;
    }
  }
  RangeSample DisjointRanges;
  findDisjointRanges(DisjointRanges, Ranges);
  return DisjointRanges;
}

void ProfileGenerator::populateBodySamplesForAllFunctions(
    const RangeSample &RangeCounter) {
  for (const auto &Range : preprocessRangeCounter(RangeCounter)) {
    uint64_t RangeBegin = Binary->offsetToVirtualAddr(Range.first.first);
    uint64_t RangeEnd = Binary->offsetToVirtualAddr(Range.first.second);
    uint64_t Count = Range.second;

    InstructionPointer IP(Binary, RangeBegin, true);
    // Disjoint ranges may have range in the middle of two instr,
    // e.g. If Instr1 at Addr1, and Instr2 at Addr2, disjoint range
    // can be Addr1+1 to Addr2-1. We should ignore such range.
    if (IP.Address > RangeEnd)
      continue;

    do {
      uint64_t Offset = Binary->virtualAddrToOffset(IP.Address);
      const SampleContextFrameVector &FrameVec =
          Binary->getFrameLocationStack(Offset);
      if (!FrameVec.empty()) {
        // FIXME: As accumulating total count per instruction caused some
        // regression, we changed to accumulate total count per byte as a
        // workaround. Tuning hotness threshold on the compiler side might be
        // necessary in the future.
        FunctionSamples &FunctionProfile = getLeafProfileAndAddTotalSamples(
            FrameVec, Count * Binary->getInstSize(Offset));
        updateBodySamplesforFunctionProfile(FunctionProfile, FrameVec.back(),
                                            Count);
      }
    } while (IP.advance() && IP.Address <= RangeEnd);
  }
}

StringRef ProfileGeneratorBase::getCalleeNameForOffset(uint64_t TargetOffset) {
  // Get the function range by branch target if it's a call branch.
  auto *FRange = Binary->findFuncRangeForStartOffset(TargetOffset);

  // We won't accumulate sample count for a range whose start is not the real
  // function entry such as outlined function or inner labels.
  if (!FRange || !FRange->IsFuncEntry)
    return StringRef();

  return FunctionSamples::getCanonicalFnName(FRange->getFuncName());
}

void ProfileGenerator::populateBoundarySamplesForAllFunctions(
    const BranchSample &BranchCounters) {
  for (const auto &Entry : BranchCounters) {
    uint64_t SourceOffset = Entry.first.first;
    uint64_t TargetOffset = Entry.first.second;
    uint64_t Count = Entry.second;
    assert(Count != 0 && "Unexpected zero weight branch");

    StringRef CalleeName = getCalleeNameForOffset(TargetOffset);
    if (CalleeName.size() == 0)
      continue;
    // Record called target sample and its count.
    const SampleContextFrameVector &FrameVec =
        Binary->getFrameLocationStack(SourceOffset);
    if (!FrameVec.empty()) {
      FunctionSamples &FunctionProfile =
          getLeafProfileAndAddTotalSamples(FrameVec, 0);
      FunctionProfile.addCalledTargetSamples(
          FrameVec.back().Location.LineOffset,
          getBaseDiscriminator(FrameVec.back().Location.Discriminator),
          CalleeName, Count);
    }
    // Add head samples for callee.
    FunctionSamples &CalleeProfile = getTopLevelFunctionProfile(CalleeName);
    CalleeProfile.addHeadSamples(Count);
  }
}

void ProfileGeneratorBase::calculateAndShowDensity(
    const SampleProfileMap &Profiles) {
  double Density = calculateDensity(Profiles, HotCountThreshold);
  showDensitySuggestion(Density);
}

FunctionSamples &CSProfileGenerator::getFunctionProfileForContext(
    const SampleContextFrameVector &Context, bool WasLeafInlined) {
  auto I = ProfileMap.find(SampleContext(Context));
  if (I == ProfileMap.end()) {
    // Save the new context for future references.
    SampleContextFrames NewContext = *Contexts.insert(Context).first;
    SampleContext FContext(NewContext, RawContext);
    auto Ret = ProfileMap.emplace(FContext, FunctionSamples());
    if (WasLeafInlined)
      FContext.setAttribute(ContextWasInlined);
    FunctionSamples &FProfile = Ret.first->second;
    FProfile.setContext(FContext);
    return Ret.first->second;
  }
  return I->second;
}

void CSProfileGenerator::generateProfile() {
  FunctionSamples::ProfileIsCSFlat = true;

  collectProfiledFunctions();

  if (Binary->usePseudoProbes()) {
    generateProbeBasedProfile();
  } else {
    generateLineNumBasedProfile();
  }

  if (Binary->getTrackFuncContextSize())
    computeSizeForProfiledFunctions();

  postProcessProfiles();
}

void CSProfileGenerator::computeSizeForProfiledFunctions() {
  std::unordered_set<const BinaryFunction *> ProfiledFunctions;
  for (auto *Func : Binary->getProfiledFunctions())
    Binary->computeInlinedContextSizeForFunc(Func);

  // Flush the symbolizer to save memory.
  Binary->flushSymbolizer();
}

void CSProfileGenerator::generateLineNumBasedProfile() {
  for (const auto &CI : SampleCounters) {
    const auto *CtxKey = cast<StringBasedCtxKey>(CI.first.getPtr());

    // Get or create function profile for the range
    FunctionSamples &FunctionProfile =
        getFunctionProfileForContext(CtxKey->Context, CtxKey->WasLeafInlined);

    // Fill in function body samples
    populateBodySamplesForFunction(FunctionProfile, CI.second.RangeCounter);
    // Fill in boundary sample counts as well as call site samples for calls
    populateBoundarySamplesForFunction(CtxKey->Context, FunctionProfile,
                                       CI.second.BranchCounter);
  }
  // Fill in call site value sample for inlined calls and also use context to
  // infer missing samples. Since we don't have call count for inlined
  // functions, we estimate it from inlinee's profile using the entry of the
  // body sample.
  populateInferredFunctionSamples();

  updateTotalSamples();
}

void CSProfileGenerator::populateBodySamplesForFunction(
    FunctionSamples &FunctionProfile, const RangeSample &RangeCounter) {
  // Compute disjoint ranges first, so we can use MAX
  // for calculating count for each location.
  RangeSample Ranges;
  findDisjointRanges(Ranges, RangeCounter);
  for (const auto &Range : Ranges) {
    uint64_t RangeBegin = Binary->offsetToVirtualAddr(Range.first.first);
    uint64_t RangeEnd = Binary->offsetToVirtualAddr(Range.first.second);
    uint64_t Count = Range.second;
    // Disjoint ranges have introduce zero-filled gap that
    // doesn't belong to current context, filter them out.
    if (Count == 0)
      continue;

    InstructionPointer IP(Binary, RangeBegin, true);
    // Disjoint ranges may have range in the middle of two instr,
    // e.g. If Instr1 at Addr1, and Instr2 at Addr2, disjoint range
    // can be Addr1+1 to Addr2-1. We should ignore such range.
    if (IP.Address > RangeEnd)
      continue;

    do {
      uint64_t Offset = Binary->virtualAddrToOffset(IP.Address);
      auto LeafLoc = Binary->getInlineLeafFrameLoc(Offset);
      if (LeafLoc.hasValue()) {
        // Recording body sample for this specific context
        updateBodySamplesforFunctionProfile(FunctionProfile, *LeafLoc, Count);
        FunctionProfile.addTotalSamples(Count);
      }
    } while (IP.advance() && IP.Address <= RangeEnd);
  }
}

void CSProfileGenerator::populateBoundarySamplesForFunction(
    SampleContextFrames ContextId, FunctionSamples &FunctionProfile,
    const BranchSample &BranchCounters) {

  for (const auto &Entry : BranchCounters) {
    uint64_t SourceOffset = Entry.first.first;
    uint64_t TargetOffset = Entry.first.second;
    uint64_t Count = Entry.second;
    assert(Count != 0 && "Unexpected zero weight branch");

    StringRef CalleeName = getCalleeNameForOffset(TargetOffset);
    if (CalleeName.size() == 0)
      continue;

    // Record called target sample and its count
    auto LeafLoc = Binary->getInlineLeafFrameLoc(SourceOffset);
    if (!LeafLoc.hasValue())
      continue;
    FunctionProfile.addCalledTargetSamples(
        LeafLoc->Location.LineOffset,
        getBaseDiscriminator(LeafLoc->Location.Discriminator), CalleeName,
        Count);

    // Record head sample for called target(callee)
    SampleContextFrameVector CalleeCtx(ContextId.begin(), ContextId.end());
    assert(CalleeCtx.back().FuncName == LeafLoc->FuncName &&
           "Leaf function name doesn't match");
    CalleeCtx.back() = *LeafLoc;
    CalleeCtx.emplace_back(CalleeName, LineLocation(0, 0));
    FunctionSamples &CalleeProfile = getFunctionProfileForContext(CalleeCtx);
    CalleeProfile.addHeadSamples(Count);
  }
}

static SampleContextFrame
getCallerContext(SampleContextFrames CalleeContext,
                 SampleContextFrameVector &CallerContext) {
  assert(CalleeContext.size() > 1 && "Unexpected empty context");
  CalleeContext = CalleeContext.drop_back();
  CallerContext.assign(CalleeContext.begin(), CalleeContext.end());
  SampleContextFrame CallerFrame = CallerContext.back();
  CallerContext.back().Location = LineLocation(0, 0);
  return CallerFrame;
}

void CSProfileGenerator::populateInferredFunctionSamples() {
  for (const auto &Item : ProfileMap) {
    const auto &CalleeContext = Item.first;
    const FunctionSamples &CalleeProfile = Item.second;

    // If we already have head sample counts, we must have value profile
    // for call sites added already. Skip to avoid double counting.
    if (CalleeProfile.getHeadSamples())
      continue;
    // If we don't have context, nothing to do for caller's call site.
    // This could happen for entry point function.
    if (CalleeContext.isBaseContext())
      continue;

    // Infer Caller's frame loc and context ID through string splitting
    SampleContextFrameVector CallerContextId;
    SampleContextFrame &&CallerLeafFrameLoc =
        getCallerContext(CalleeContext.getContextFrames(), CallerContextId);
    SampleContextFrames CallerContext(CallerContextId);

    // It's possible that we haven't seen any sample directly in the caller,
    // in which case CallerProfile will not exist. But we can't modify
    // ProfileMap while iterating it.
    // TODO: created function profile for those callers too
    if (ProfileMap.find(CallerContext) == ProfileMap.end())
      continue;
    FunctionSamples &CallerProfile = ProfileMap[CallerContext];

    // Since we don't have call count for inlined functions, we
    // estimate it from inlinee's profile using entry body sample.
    uint64_t EstimatedCallCount = CalleeProfile.getEntrySamples();
    // If we don't have samples with location, use 1 to indicate live.
    if (!EstimatedCallCount && !CalleeProfile.getBodySamples().size())
      EstimatedCallCount = 1;
    CallerProfile.addCalledTargetSamples(
        CallerLeafFrameLoc.Location.LineOffset,
        CallerLeafFrameLoc.Location.Discriminator,
        CalleeProfile.getContext().getName(), EstimatedCallCount);
    CallerProfile.addBodySamples(CallerLeafFrameLoc.Location.LineOffset,
                                 CallerLeafFrameLoc.Location.Discriminator,
                                 EstimatedCallCount);
    CallerProfile.addTotalSamples(EstimatedCallCount);
  }
}

void CSProfileGenerator::postProcessProfiles() {
  // Compute hot/cold threshold based on profile. This will be used for cold
  // context profile merging/trimming.
  computeSummaryAndThreshold();

  // Run global pre-inliner to adjust/merge context profile based on estimated
  // inline decisions.
  if (EnableCSPreInliner) {
    CSPreInliner(ProfileMap, *Binary, HotCountThreshold, ColdCountThreshold)
        .run();
    // Turn off the profile merger by default unless it is explicitly enabled.
    if (!CSProfMergeColdContext.getNumOccurrences())
      CSProfMergeColdContext = false;
  }

  // Trim and merge cold context profile using cold threshold above.
  if (TrimColdProfile || CSProfMergeColdContext) {
    SampleContextTrimmer(ProfileMap)
        .trimAndMergeColdContextProfiles(
            HotCountThreshold, TrimColdProfile, CSProfMergeColdContext,
            CSProfMaxColdContextDepth, EnableCSPreInliner);
  }

  // Merge function samples of CS profile to calculate profile density.
  sampleprof::SampleProfileMap ContextLessProfiles;
  for (const auto &I : ProfileMap) {
    ContextLessProfiles[I.second.getName()].merge(I.second);
  }

  calculateAndShowDensity(ContextLessProfiles);
  if (GenCSNestedProfile) {
    CSProfileConverter CSConverter(ProfileMap);
    CSConverter.convertProfiles();
    FunctionSamples::ProfileIsCSFlat = false;
    FunctionSamples::ProfileIsCSNested = EnableCSPreInliner;
  }
}

void ProfileGeneratorBase::computeSummaryAndThreshold() {
  SampleProfileSummaryBuilder Builder(ProfileSummaryBuilder::DefaultCutoffs);
  auto Summary = Builder.computeSummaryForProfiles(ProfileMap);
  HotCountThreshold = ProfileSummaryBuilder::getHotCountThreshold(
      (Summary->getDetailedSummary()));
  ColdCountThreshold = ProfileSummaryBuilder::getColdCountThreshold(
      (Summary->getDetailedSummary()));
}

void ProfileGeneratorBase::extractProbesFromRange(
    const RangeSample &RangeCounter, ProbeCounterMap &ProbeCounter,
    bool FindDisjointRanges) {
  const RangeSample *PRanges = &RangeCounter;
  RangeSample Ranges;
  if (FindDisjointRanges) {
    findDisjointRanges(Ranges, RangeCounter);
    PRanges = &Ranges;
  }

  for (const auto &Range : *PRanges) {
    uint64_t RangeBegin = Binary->offsetToVirtualAddr(Range.first.first);
    uint64_t RangeEnd = Binary->offsetToVirtualAddr(Range.first.second);
    uint64_t Count = Range.second;

    InstructionPointer IP(Binary, RangeBegin, true);
    // Disjoint ranges may have range in the middle of two instr,
    // e.g. If Instr1 at Addr1, and Instr2 at Addr2, disjoint range
    // can be Addr1+1 to Addr2-1. We should ignore such range.
    if (IP.Address > RangeEnd)
      continue;

    do {
      const AddressProbesMap &Address2ProbesMap =
          Binary->getAddress2ProbesMap();
      auto It = Address2ProbesMap.find(IP.Address);
      if (It != Address2ProbesMap.end()) {
        for (const auto &Probe : It->second) {
          ProbeCounter[&Probe] += Count;
        }
      }
    } while (IP.advance() && IP.Address <= RangeEnd);
  }
}

static void
extractPrefixContextStack(SampleContextFrameVector &ContextStack,
                          const SmallVectorImpl<uint64_t> &Addresses,
                          ProfiledBinary *Binary) {
  SmallVector<const MCDecodedPseudoProbe *, 16> Probes;
  for (auto Addr : reverse(Addresses)) {
    const MCDecodedPseudoProbe *CallProbe = Binary->getCallProbeForAddr(Addr);
    // These could be the cases when a probe is not found at a calliste. Cutting
    // off the context from here since the inliner will not know how to consume
    // a context with unknown callsites.
    // 1. for functions that are not sampled when
    // --decode-probe-for-profiled-functions-only is on.
    // 2. for a merged callsite. Callsite merging may cause the loss of original
    // probe IDs.
    // 3. for an external callsite.
    if (!CallProbe)
      break;
    Probes.push_back(CallProbe);
  }

  std::reverse(Probes.begin(), Probes.end());

  // Extract context stack for reusing, leaf context stack will be added
  // compressed while looking up function profile.
  for (const auto *P : Probes) {
    Binary->getInlineContextForProbe(P, ContextStack, true);
  }
}

void CSProfileGenerator::generateProbeBasedProfile() {
  Binary->decodePseudoProbe();
  // Enable pseudo probe functionalities in SampleProf
  FunctionSamples::ProfileIsProbeBased = true;
  for (const auto &CI : SampleCounters) {
    const AddrBasedCtxKey *CtxKey =
        dyn_cast<AddrBasedCtxKey>(CI.first.getPtr());
    SampleContextFrameVector ContextStack;
    extractPrefixContextStack(ContextStack, CtxKey->Context, Binary);
    // Fill in function body samples from probes, also infer caller's samples
    // from callee's probe
    populateBodySamplesWithProbes(CI.second.RangeCounter, ContextStack);
    // Fill in boundary samples for a call probe
    populateBoundarySamplesWithProbes(CI.second.BranchCounter, ContextStack);
  }
}

void CSProfileGenerator::populateBodySamplesWithProbes(
    const RangeSample &RangeCounter, SampleContextFrames ContextStack) {
  ProbeCounterMap ProbeCounter;
  // Extract the top frame probes by looking up each address among the range in
  // the Address2ProbeMap
  extractProbesFromRange(RangeCounter, ProbeCounter);
  std::unordered_map<MCDecodedPseudoProbeInlineTree *,
                     std::unordered_set<FunctionSamples *>>
      FrameSamples;
  for (const auto &PI : ProbeCounter) {
    const MCDecodedPseudoProbe *Probe = PI.first;
    uint64_t Count = PI.second;
    // Disjoint ranges have introduce zero-filled gap that
    // doesn't belong to current context, filter them out.
    if (!Probe->isBlock() || Count == 0)
      continue;
    FunctionSamples &FunctionProfile =
        getFunctionProfileForLeafProbe(ContextStack, Probe);
    // Record the current frame and FunctionProfile whenever samples are
    // collected for non-danglie probes. This is for reporting all of the
    // zero count probes of the frame later.
    FrameSamples[Probe->getInlineTreeNode()].insert(&FunctionProfile);
    FunctionProfile.addBodySamplesForProbe(Probe->getIndex(), Count);
    FunctionProfile.addTotalSamples(Count);
    if (Probe->isEntry()) {
      FunctionProfile.addHeadSamples(Count);
      // Look up for the caller's function profile
      const auto *InlinerDesc = Binary->getInlinerDescForProbe(Probe);
      SampleContextFrames CalleeContextId =
          FunctionProfile.getContext().getContextFrames();
      if (InlinerDesc != nullptr && CalleeContextId.size() > 1) {
        // Since the context id will be compressed, we have to use callee's
        // context id to infer caller's context id to ensure they share the
        // same context prefix.
        SampleContextFrameVector CallerContextId;
        SampleContextFrame &&CallerLeafFrameLoc =
            getCallerContext(CalleeContextId, CallerContextId);
        uint64_t CallerIndex = CallerLeafFrameLoc.Location.LineOffset;
        assert(CallerIndex &&
               "Inferred caller's location index shouldn't be zero!");
        FunctionSamples &CallerProfile =
            getFunctionProfileForContext(CallerContextId);
        CallerProfile.setFunctionHash(InlinerDesc->FuncHash);
        CallerProfile.addBodySamples(CallerIndex, 0, Count);
        CallerProfile.addTotalSamples(Count);
        CallerProfile.addCalledTargetSamples(
            CallerIndex, 0, FunctionProfile.getContext().getName(), Count);
      }
    }
  }

  // Assign zero count for remaining probes without sample hits to
  // differentiate from probes optimized away, of which the counts are unknown
  // and will be inferred by the compiler.
  for (auto &I : FrameSamples) {
    for (auto *FunctionProfile : I.second) {
      for (auto *Probe : I.first->getProbes()) {
        FunctionProfile->addBodySamplesForProbe(Probe->getIndex(), 0);
      }
    }
  }
}

void CSProfileGenerator::populateBoundarySamplesWithProbes(
    const BranchSample &BranchCounter, SampleContextFrames ContextStack) {
  for (const auto &BI : BranchCounter) {
    uint64_t SourceOffset = BI.first.first;
    uint64_t TargetOffset = BI.first.second;
    uint64_t Count = BI.second;
    uint64_t SourceAddress = Binary->offsetToVirtualAddr(SourceOffset);
    const MCDecodedPseudoProbe *CallProbe =
        Binary->getCallProbeForAddr(SourceAddress);
    if (CallProbe == nullptr)
      continue;
    FunctionSamples &FunctionProfile =
        getFunctionProfileForLeafProbe(ContextStack, CallProbe);
    FunctionProfile.addBodySamples(CallProbe->getIndex(), 0, Count);
    FunctionProfile.addTotalSamples(Count);
    StringRef CalleeName = getCalleeNameForOffset(TargetOffset);
    if (CalleeName.size() == 0)
      continue;
    FunctionProfile.addCalledTargetSamples(CallProbe->getIndex(), 0, CalleeName,
                                           Count);
  }
}

FunctionSamples &CSProfileGenerator::getFunctionProfileForLeafProbe(
    SampleContextFrames ContextStack, const MCDecodedPseudoProbe *LeafProbe) {

  // Explicitly copy the context for appending the leaf context
  SampleContextFrameVector NewContextStack(ContextStack.begin(),
                                           ContextStack.end());
  Binary->getInlineContextForProbe(LeafProbe, NewContextStack, true);
  // For leaf inlined context with the top frame, we should strip off the top
  // frame's probe id, like:
  // Inlined stack: [foo:1, bar:2], the ContextId will be "foo:1 @ bar"
  auto LeafFrame = NewContextStack.back();
  LeafFrame.Location = LineLocation(0, 0);
  NewContextStack.pop_back();
  // Compress the context string except for the leaf frame
  CSProfileGenerator::compressRecursionContext(NewContextStack);
  CSProfileGenerator::trimContext(NewContextStack);
  NewContextStack.push_back(LeafFrame);

  const auto *FuncDesc = Binary->getFuncDescForGUID(LeafProbe->getGuid());
  bool WasLeafInlined = LeafProbe->getInlineTreeNode()->hasInlineSite();
  FunctionSamples &FunctionProile =
      getFunctionProfileForContext(NewContextStack, WasLeafInlined);
  FunctionProile.setFunctionHash(FuncDesc->FuncHash);
  return FunctionProile;
}

} // end namespace sampleprof
} // end namespace llvm