/build/source/clang/lib/CodeGen/CoverageMappingGen.cpp

Bug Summary

File:	build/source/clang/lib/CodeGen/CoverageMappingGen.cpp
Warning:	line 279, column 26 Called C++ object pointer is null
Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name CoverageMappingGen.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/source/build-llvm -resource-dir /usr/lib/llvm-17/lib/clang/17 -I tools/clang/lib/CodeGen -I /build/source/clang/lib/CodeGen -I /build/source/clang/include -I tools/clang/include -I include -I /build/source/llvm/include -D _DEBUG -D _GLIBCXX_ASSERTIONS -D _GNU_SOURCE -D _LIBCPP_ENABLE_ASSERTIONS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-17/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/source/build-llvm=build-llvm -fmacro-prefix-map=/build/source/= -fcoverage-prefix-map=/build/source/build-llvm=build-llvm -fcoverage-prefix-map=/build/source/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/source/build-llvm -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2023-05-10-133810-16478-1 -x c++ /build/source/clang/lib/CodeGen/CoverageMappingGen.cpp
1//===--- CoverageMappingGen.cpp - Coverage mapping generation ---*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Instrumentation-based code coverage mapping generator
10//
11//===----------------------------------------------------------------------===//

13#include "CoverageMappingGen.h"
14#include "CodeGenFunction.h"
15#include "clang/AST/StmtVisitor.h"
16#include "clang/Basic/Diagnostic.h"
17#include "clang/Basic/FileManager.h"
18#include "clang/Frontend/FrontendDiagnostic.h"
19#include "clang/Lex/Lexer.h"
20#include "llvm/ADT/SmallSet.h"
21#include "llvm/ADT/StringExtras.h"
22#include "llvm/ProfileData/Coverage/CoverageMapping.h"
23#include "llvm/ProfileData/Coverage/CoverageMappingReader.h"
24#include "llvm/ProfileData/Coverage/CoverageMappingWriter.h"
25#include "llvm/ProfileData/InstrProfReader.h"
26#include "llvm/Support/FileSystem.h"
27#include "llvm/Support/Path.h"
28#include <optional>

30// This selects the coverage mapping format defined when `InstrProfData.inc`
31// is textually included.
32#define COVMAP_V3

34static llvm::cl::opt<bool> EmptyLineCommentCoverage(
  "emptyline-comment-coverage",
  llvm::cl::desc("Emit emptylines and comment lines as skipped regions (only "
                 "disable it on test)"),
  llvm::cl::init(true), llvm::cl::Hidden);

40static llvm::cl::opt<bool> SystemHeadersCoverage(
  "system-headers-coverage",
  llvm::cl::desc("Enable collecting coverage from system headers"),
  llvm::cl::init(false), llvm::cl::Hidden);

45using namespace clang;
46using namespace CodeGen;
47using namespace llvm::coverage;

49CoverageSourceInfo *
50CoverageMappingModuleGen::setUpCoverageCallbacks(Preprocessor &PP) {
CoverageSourceInfo *CoverageInfo =
    new CoverageSourceInfo(PP.getSourceManager());
PP.addPPCallbacks(std::unique_ptr<PPCallbacks>(CoverageInfo));
if (EmptyLineCommentCoverage) {
  PP.addCommentHandler(CoverageInfo);
  PP.setEmptylineHandler(CoverageInfo);
  PP.setPreprocessToken(true);
  PP.setTokenWatcher([CoverageInfo](clang::Token Tok) {
    // Update previous token location.
    CoverageInfo->PrevTokLoc = Tok.getLocation();
    if (Tok.getKind() != clang::tok::eod)
      CoverageInfo->updateNextTokLoc(Tok.getLocation());
  });
}
return CoverageInfo;
66}

68void CoverageSourceInfo::AddSkippedRange(SourceRange Range,
                                       SkippedRange::Kind RangeKind) {
if (EmptyLineCommentCoverage && !SkippedRanges.empty() &&
    PrevTokLoc == SkippedRanges.back().PrevTokLoc &&
    SourceMgr.isWrittenInSameFile(SkippedRanges.back().Range.getEnd(),
                                  Range.getBegin()))
  SkippedRanges.back().Range.setEnd(Range.getEnd());
else
  SkippedRanges.push_back({Range, RangeKind, PrevTokLoc});
77}

79void CoverageSourceInfo::SourceRangeSkipped(SourceRange Range, SourceLocation) {
AddSkippedRange(Range, SkippedRange::PPIfElse);
81}

83void CoverageSourceInfo::HandleEmptyline(SourceRange Range) {
AddSkippedRange(Range, SkippedRange::EmptyLine);
85}

87bool CoverageSourceInfo::HandleComment(Preprocessor &PP, SourceRange Range) {
AddSkippedRange(Range, SkippedRange::Comment);
return false;
90}

92void CoverageSourceInfo::updateNextTokLoc(SourceLocation Loc) {
if (!SkippedRanges.empty() && SkippedRanges.back().NextTokLoc.isInvalid())
  SkippedRanges.back().NextTokLoc = Loc;
95}

97namespace {

99/// A region of source code that can be mapped to a counter.
100class SourceMappingRegion {
/// Primary Counter that is also used for Branch Regions for "True" branches.
Counter Count;

/// Secondary Counter used for Branch Regions for "False" branches.
std::optional<Counter> FalseCount;

/// The region's starting location.
std::optional<SourceLocation> LocStart;

/// The region's ending location.
std::optional<SourceLocation> LocEnd;

/// Whether this region is a gap region. The count from a gap region is set
/// as the line execution count if there are no other regions on the line.
bool GapRegion;

117public:
SourceMappingRegion(Counter Count, std::optional<SourceLocation> LocStart,
                    std::optional<SourceLocation> LocEnd,
                    bool GapRegion = false)
    : Count(Count), LocStart(LocStart), LocEnd(LocEnd), GapRegion(GapRegion) {
}

SourceMappingRegion(Counter Count, std::optional<Counter> FalseCount,
                    std::optional<SourceLocation> LocStart,
                    std::optional<SourceLocation> LocEnd,
                    bool GapRegion = false)
    : Count(Count), FalseCount(FalseCount), LocStart(LocStart),
      LocEnd(LocEnd), GapRegion(GapRegion) {}

const Counter &getCounter() const { return Count; }

const Counter &getFalseCounter() const {
  assert(FalseCount && "Region has no alternate counter")(static_cast <bool> (FalseCount && "Region has no alternate counter"
) ? void (0) : __assert_fail ("FalseCount && \"Region has no alternate counter\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 134, __extension__
 __PRETTY_FUNCTION__));
  return *FalseCount;
}

void setCounter(Counter C) { Count = C; }

bool hasStartLoc() const { return LocStart.has_value(); }

void setStartLoc(SourceLocation Loc) { LocStart = Loc; }

SourceLocation getBeginLoc() const {
  assert(LocStart && "Region has no start location")(static_cast <bool> (LocStart && "Region has no start location"
) ? void (0) : __assert_fail ("LocStart && \"Region has no start location\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 145, __extension__
 __PRETTY_FUNCTION__));
  return *LocStart;
}

bool hasEndLoc() const { return LocEnd.has_value(); }

void setEndLoc(SourceLocation Loc) {
  assert(Loc.isValid() && "Setting an invalid end location")(static_cast <bool> (Loc.isValid() && "Setting an invalid end location"
) ? void (0) : __assert_fail ("Loc.isValid() && \"Setting an invalid end location\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 152, __extension__
 __PRETTY_FUNCTION__));
  LocEnd = Loc;
}

SourceLocation getEndLoc() const {
  assert(LocEnd && "Region has no end location")(static_cast <bool> (LocEnd && "Region has no end location"
) ? void (0) : __assert_fail ("LocEnd && \"Region has no end location\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 157, __extension__
 __PRETTY_FUNCTION__));
  return *LocEnd;
}

bool isGap() const { return GapRegion; }

void setGap(bool Gap) { GapRegion = Gap; }

bool isBranch() const { return FalseCount.has_value(); }
166};

168/// Spelling locations for the start and end of a source region.
169struct SpellingRegion {
/// The line where the region starts.
unsigned LineStart;

/// The column where the region starts.
unsigned ColumnStart;

/// The line where the region ends.
unsigned LineEnd;

/// The column where the region ends.
unsigned ColumnEnd;

SpellingRegion(SourceManager &SM, SourceLocation LocStart,
               SourceLocation LocEnd) {
  LineStart = SM.getSpellingLineNumber(LocStart);
  ColumnStart = SM.getSpellingColumnNumber(LocStart);
  LineEnd = SM.getSpellingLineNumber(LocEnd);
  ColumnEnd = SM.getSpellingColumnNumber(LocEnd);
}

SpellingRegion(SourceManager &SM, SourceMappingRegion &R)
    : SpellingRegion(SM, R.getBeginLoc(), R.getEndLoc()) {}

/// Check if the start and end locations appear in source order, i.e
/// top->bottom, left->right.
bool isInSourceOrder() const {
  return (LineStart < LineEnd) ||
         (LineStart == LineEnd && ColumnStart <= ColumnEnd);
}
199};

201/// Provides the common functionality for the different
202/// coverage mapping region builders.
203class CoverageMappingBuilder {
204public:
CoverageMappingModuleGen &CVM;
SourceManager &SM;
const LangOptions &LangOpts;

209private:
/// Map of clang's FileIDs to IDs used for coverage mapping.
llvm::SmallDenseMap<FileID, std::pair<unsigned, SourceLocation>, 8>
    FileIDMapping;

214public:
/// The coverage mapping regions for this function
llvm::SmallVector<CounterMappingRegion, 32> MappingRegions;
/// The source mapping regions for this function.
std::vector<SourceMappingRegion> SourceRegions;

/// A set of regions which can be used as a filter.
///
/// It is produced by emitExpansionRegions() and is used in
/// emitSourceRegions() to suppress producing code regions if
/// the same area is covered by expansion regions.
typedef llvm::SmallSet<std::pair<SourceLocation, SourceLocation>, 8>
    SourceRegionFilter;

CoverageMappingBuilder(CoverageMappingModuleGen &CVM, SourceManager &SM,
                       const LangOptions &LangOpts)
    : CVM(CVM), SM(SM), LangOpts(LangOpts) {}

/// Return the precise end location for the given token.
SourceLocation getPreciseTokenLocEnd(SourceLocation Loc) {
  // We avoid getLocForEndOfToken here, because it doesn't do what we want for
  // macro locations, which we just treat as expanded files.
  unsigned TokLen =
      Lexer::MeasureTokenLength(SM.getSpellingLoc(Loc), SM, LangOpts);
  return Loc.getLocWithOffset(TokLen);
}

/// Return the start location of an included file or expanded macro.
SourceLocation getStartOfFileOrMacro(SourceLocation Loc) {
  if (Loc.isMacroID())
    return Loc.getLocWithOffset(-SM.getFileOffset(Loc));
  return SM.getLocForStartOfFile(SM.getFileID(Loc));
}

/// Return the end location of an included file or expanded macro.
SourceLocation getEndOfFileOrMacro(SourceLocation Loc) {
  if (Loc.isMacroID())
    return Loc.getLocWithOffset(SM.getFileIDSize(SM.getFileID(Loc)) -
                                SM.getFileOffset(Loc));
  return SM.getLocForEndOfFile(SM.getFileID(Loc));
}

/// Find out where the current file is included or macro is expanded.
SourceLocation getIncludeOrExpansionLoc(SourceLocation Loc) {
  return Loc.isMacroID() ? SM.getImmediateExpansionRange(Loc).getBegin()
                         : SM.getIncludeLoc(SM.getFileID(Loc));
}

/// Return true if \c Loc is a location in a built-in macro.
bool isInBuiltin(SourceLocation Loc) {
  return SM.getBufferName(SM.getSpellingLoc(Loc)) == "<built-in>";
}

/// Check whether \c Loc is included or expanded from \c Parent.
bool isNestedIn(SourceLocation Loc, FileID Parent) {
  do {
    Loc = getIncludeOrExpansionLoc(Loc);
    if (Loc.isInvalid())
      return false;
  } while (!SM.isInFileID(Loc, Parent));
  return true;
}

/// Get the start of \c S ignoring macro arguments and builtin macros.
SourceLocation getStart(const Stmt *S) {
  SourceLocation Loc = S->getBeginLoc();
14
←
Called C++ object pointer is null
  while (SM.isMacroArgExpansion(Loc) || isInBuiltin(Loc))
    Loc = SM.getImmediateExpansionRange(Loc).getBegin();
  return Loc;
}

/// Get the end of \c S ignoring macro arguments and builtin macros.
SourceLocation getEnd(const Stmt *S) {
  SourceLocation Loc = S->getEndLoc();
  while (SM.isMacroArgExpansion(Loc) || isInBuiltin(Loc))
    Loc = SM.getImmediateExpansionRange(Loc).getBegin();
  return getPreciseTokenLocEnd(Loc);
}

/// Find the set of files we have regions for and assign IDs
///
/// Fills \c Mapping with the virtual file mapping needed to write out
/// coverage and collects the necessary file information to emit source and
/// expansion regions.
void gatherFileIDs(SmallVectorImpl<unsigned> &Mapping) {
  FileIDMapping.clear();

  llvm::SmallSet<FileID, 8> Visited;
  SmallVector<std::pair<SourceLocation, unsigned>, 8> FileLocs;
  for (const auto &Region : SourceRegions) {
    SourceLocation Loc = Region.getBeginLoc();
    FileID File = SM.getFileID(Loc);
    if (!Visited.insert(File).second)
      continue;

    // Do not map FileID's associated with system headers unless collecting
    // coverage from system headers is explicitly enabled.
    if (!SystemHeadersCoverage && SM.isInSystemHeader(SM.getSpellingLoc(Loc)))
      continue;

    unsigned Depth = 0;
    for (SourceLocation Parent = getIncludeOrExpansionLoc(Loc);
         Parent.isValid(); Parent = getIncludeOrExpansionLoc(Parent))
      ++Depth;
    FileLocs.push_back(std::make_pair(Loc, Depth));
  }
  llvm::stable_sort(FileLocs, llvm::less_second());

  for (const auto &FL : FileLocs) {
    SourceLocation Loc = FL.first;
    FileID SpellingFile = SM.getDecomposedSpellingLoc(Loc).first;
    auto Entry = SM.getFileEntryForID(SpellingFile);
    if (!Entry)
      continue;

    FileIDMapping[SM.getFileID(Loc)] = std::make_pair(Mapping.size(), Loc);
    Mapping.push_back(CVM.getFileID(Entry));
  }
}

/// Get the coverage mapping file ID for \c Loc.
///
/// If such file id doesn't exist, return std::nullopt.
std::optional<unsigned> getCoverageFileID(SourceLocation Loc) {
  auto Mapping = FileIDMapping.find(SM.getFileID(Loc));
  if (Mapping != FileIDMapping.end())
    return Mapping->second.first;
  return std::nullopt;
}

/// This shrinks the skipped range if it spans a line that contains a
/// non-comment token. If shrinking the skipped range would make it empty,
/// this returns std::nullopt.
/// Note this function can potentially be expensive because
/// getSpellingLineNumber uses getLineNumber, which is expensive.
std::optional<SpellingRegion> adjustSkippedRange(SourceManager &SM,
                                                 SourceLocation LocStart,
                                                 SourceLocation LocEnd,
                                                 SourceLocation PrevTokLoc,
                                                 SourceLocation NextTokLoc) {
  SpellingRegion SR{SM, LocStart, LocEnd};
  SR.ColumnStart = 1;
  if (PrevTokLoc.isValid() && SM.isWrittenInSameFile(LocStart, PrevTokLoc) &&
      SR.LineStart == SM.getSpellingLineNumber(PrevTokLoc))
    SR.LineStart++;
  if (NextTokLoc.isValid() && SM.isWrittenInSameFile(LocEnd, NextTokLoc) &&
      SR.LineEnd == SM.getSpellingLineNumber(NextTokLoc)) {
    SR.LineEnd--;
    SR.ColumnEnd++;
  }
  if (SR.isInSourceOrder())
    return SR;
  return std::nullopt;
}

/// Gather all the regions that were skipped by the preprocessor
/// using the constructs like #if or comments.
void gatherSkippedRegions() {
  /// An array of the minimum lineStarts and the maximum lineEnds
  /// for mapping regions from the appropriate source files.
  llvm::SmallVector<std::pair<unsigned, unsigned>, 8> FileLineRanges;
  FileLineRanges.resize(
      FileIDMapping.size(),
      std::make_pair(std::numeric_limits<unsigned>::max(), 0));
  for (const auto &R : MappingRegions) {
    FileLineRanges[R.FileID].first =
        std::min(FileLineRanges[R.FileID].first, R.LineStart);
    FileLineRanges[R.FileID].second =
        std::max(FileLineRanges[R.FileID].second, R.LineEnd);
  }

  auto SkippedRanges = CVM.getSourceInfo().getSkippedRanges();
  for (auto &I : SkippedRanges) {
    SourceRange Range = I.Range;
    auto LocStart = Range.getBegin();
    auto LocEnd = Range.getEnd();
    assert(SM.isWrittenInSameFile(LocStart, LocEnd) &&(static_cast <bool> (SM.isWrittenInSameFile(LocStart, LocEnd
) && "region spans multiple files") ? void (0) : __assert_fail
 ("SM.isWrittenInSameFile(LocStart, LocEnd) && \"region spans multiple files\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 391, __extension__
 __PRETTY_FUNCTION__))
           "region spans multiple files")(static_cast <bool> (SM.isWrittenInSameFile(LocStart, LocEnd
) && "region spans multiple files") ? void (0) : __assert_fail
 ("SM.isWrittenInSameFile(LocStart, LocEnd) && \"region spans multiple files\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 391, __extension__
 __PRETTY_FUNCTION__));

    auto CovFileID = getCoverageFileID(LocStart);
    if (!CovFileID)
      continue;
    std::optional<SpellingRegion> SR;
    if (I.isComment())
      SR = adjustSkippedRange(SM, LocStart, LocEnd, I.PrevTokLoc,
                              I.NextTokLoc);
    else if (I.isPPIfElse() || I.isEmptyLine())
      SR = {SM, LocStart, LocEnd};

    if (!SR)
      continue;
    auto Region = CounterMappingRegion::makeSkipped(
        *CovFileID, SR->LineStart, SR->ColumnStart, SR->LineEnd,
        SR->ColumnEnd);
    // Make sure that we only collect the regions that are inside
    // the source code of this function.
    if (Region.LineStart >= FileLineRanges[*CovFileID].first &&
        Region.LineEnd <= FileLineRanges[*CovFileID].second)
      MappingRegions.push_back(Region);
  }
}

/// Generate the coverage counter mapping regions from collected
/// source regions.
void emitSourceRegions(const SourceRegionFilter &Filter) {
  for (const auto &Region : SourceRegions) {
    assert(Region.hasEndLoc() && "incomplete region")(static_cast <bool> (Region.hasEndLoc() && "incomplete region"
) ? void (0) : __assert_fail ("Region.hasEndLoc() && \"incomplete region\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 420, __extension__
 __PRETTY_FUNCTION__));

    SourceLocation LocStart = Region.getBeginLoc();
    assert(SM.getFileID(LocStart).isValid() && "region in invalid file")(static_cast <bool> (SM.getFileID(LocStart).isValid() &&
 "region in invalid file") ? void (0) : __assert_fail ("SM.getFileID(LocStart).isValid() && \"region in invalid file\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 423, __extension__
 __PRETTY_FUNCTION__));

    // Ignore regions from system headers unless collecting coverage from
    // system headers is explicitly enabled.
    if (!SystemHeadersCoverage &&
        SM.isInSystemHeader(SM.getSpellingLoc(LocStart)))
      continue;

    auto CovFileID = getCoverageFileID(LocStart);
    // Ignore regions that don't have a file, such as builtin macros.
    if (!CovFileID)
      continue;

    SourceLocation LocEnd = Region.getEndLoc();
    assert(SM.isWrittenInSameFile(LocStart, LocEnd) &&(static_cast <bool> (SM.isWrittenInSameFile(LocStart, LocEnd
) && "region spans multiple files") ? void (0) : __assert_fail
 ("SM.isWrittenInSameFile(LocStart, LocEnd) && \"region spans multiple files\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 438, __extension__
 __PRETTY_FUNCTION__))
           "region spans multiple files")(static_cast <bool> (SM.isWrittenInSameFile(LocStart, LocEnd
) && "region spans multiple files") ? void (0) : __assert_fail
 ("SM.isWrittenInSameFile(LocStart, LocEnd) && \"region spans multiple files\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 438, __extension__
 __PRETTY_FUNCTION__));

    // Don't add code regions for the area covered by expansion regions.
    // This not only suppresses redundant regions, but sometimes prevents
    // creating regions with wrong counters if, for example, a statement's
    // body ends at the end of a nested macro.
    if (Filter.count(std::make_pair(LocStart, LocEnd)))
      continue;

    // Find the spelling locations for the mapping region.
    SpellingRegion SR{SM, LocStart, LocEnd};
    assert(SR.isInSourceOrder() && "region start and end out of order")(static_cast <bool> (SR.isInSourceOrder() && "region start and end out of order"
) ? void (0) : __assert_fail ("SR.isInSourceOrder() && \"region start and end out of order\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 449, __extension__
 __PRETTY_FUNCTION__));

    if (Region.isGap()) {
      MappingRegions.push_back(CounterMappingRegion::makeGapRegion(
          Region.getCounter(), *CovFileID, SR.LineStart, SR.ColumnStart,
          SR.LineEnd, SR.ColumnEnd));
    } else if (Region.isBranch()) {
      MappingRegions.push_back(CounterMappingRegion::makeBranchRegion(
          Region.getCounter(), Region.getFalseCounter(), *CovFileID,
          SR.LineStart, SR.ColumnStart, SR.LineEnd, SR.ColumnEnd));
    } else {
      MappingRegions.push_back(CounterMappingRegion::makeRegion(
          Region.getCounter(), *CovFileID, SR.LineStart, SR.ColumnStart,
          SR.LineEnd, SR.ColumnEnd));
    }
  }
}

/// Generate expansion regions for each virtual file we've seen.
SourceRegionFilter emitExpansionRegions() {
  SourceRegionFilter Filter;
  for (const auto &FM : FileIDMapping) {
    SourceLocation ExpandedLoc = FM.second.second;
    SourceLocation ParentLoc = getIncludeOrExpansionLoc(ExpandedLoc);
    if (ParentLoc.isInvalid())
      continue;

    auto ParentFileID = getCoverageFileID(ParentLoc);
    if (!ParentFileID)
      continue;
    auto ExpandedFileID = getCoverageFileID(ExpandedLoc);
    assert(ExpandedFileID && "expansion in uncovered file")(static_cast <bool> (ExpandedFileID && "expansion in uncovered file"
) ? void (0) : __assert_fail ("ExpandedFileID && \"expansion in uncovered file\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 480, __extension__
 __PRETTY_FUNCTION__));

    SourceLocation LocEnd = getPreciseTokenLocEnd(ParentLoc);
    assert(SM.isWrittenInSameFile(ParentLoc, LocEnd) &&(static_cast <bool> (SM.isWrittenInSameFile(ParentLoc, LocEnd
) && "region spans multiple files") ? void (0) : __assert_fail
 ("SM.isWrittenInSameFile(ParentLoc, LocEnd) && \"region spans multiple files\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 484, __extension__
 __PRETTY_FUNCTION__))
           "region spans multiple files")(static_cast <bool> (SM.isWrittenInSameFile(ParentLoc, LocEnd
) && "region spans multiple files") ? void (0) : __assert_fail
 ("SM.isWrittenInSameFile(ParentLoc, LocEnd) && \"region spans multiple files\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 484, __extension__
 __PRETTY_FUNCTION__));
    Filter.insert(std::make_pair(ParentLoc, LocEnd));

    SpellingRegion SR{SM, ParentLoc, LocEnd};
    assert(SR.isInSourceOrder() && "region start and end out of order")(static_cast <bool> (SR.isInSourceOrder() && "region start and end out of order"
) ? void (0) : __assert_fail ("SR.isInSourceOrder() && \"region start and end out of order\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 488, __extension__
 __PRETTY_FUNCTION__));
    MappingRegions.push_back(CounterMappingRegion::makeExpansion(
        *ParentFileID, *ExpandedFileID, SR.LineStart, SR.ColumnStart,
        SR.LineEnd, SR.ColumnEnd));
  }
  return Filter;
}
495};

497/// Creates unreachable coverage regions for the functions that
498/// are not emitted.
499struct EmptyCoverageMappingBuilder : public CoverageMappingBuilder {
EmptyCoverageMappingBuilder(CoverageMappingModuleGen &CVM, SourceManager &SM,
                            const LangOptions &LangOpts)
    : CoverageMappingBuilder(CVM, SM, LangOpts) {}

void VisitDecl(const Decl *D) {
  if (!D->hasBody())
    return;
  auto Body = D->getBody();
  SourceLocation Start = getStart(Body);
  SourceLocation End = getEnd(Body);
  if (!SM.isWrittenInSameFile(Start, End)) {
    // Walk up to find the common ancestor.
    // Correct the locations accordingly.
    FileID StartFileID = SM.getFileID(Start);
    FileID EndFileID = SM.getFileID(End);
    while (StartFileID != EndFileID && !isNestedIn(End, StartFileID)) {
      Start = getIncludeOrExpansionLoc(Start);
      assert(Start.isValid() &&(static_cast <bool> (Start.isValid() && "Declaration start location not nested within a known region"
) ? void (0) : __assert_fail ("Start.isValid() && \"Declaration start location not nested within a known region\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 518, __extension__
 __PRETTY_FUNCTION__))
             "Declaration start location not nested within a known region")(static_cast <bool> (Start.isValid() && "Declaration start location not nested within a known region"
) ? void (0) : __assert_fail ("Start.isValid() && \"Declaration start location not nested within a known region\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 518, __extension__
 __PRETTY_FUNCTION__));
      StartFileID = SM.getFileID(Start);
    }
    while (StartFileID != EndFileID) {
      End = getPreciseTokenLocEnd(getIncludeOrExpansionLoc(End));
      assert(End.isValid() &&(static_cast <bool> (End.isValid() && "Declaration end location not nested within a known region"
) ? void (0) : __assert_fail ("End.isValid() && \"Declaration end location not nested within a known region\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 524, __extension__
 __PRETTY_FUNCTION__))
             "Declaration end location not nested within a known region")(static_cast <bool> (End.isValid() && "Declaration end location not nested within a known region"
) ? void (0) : __assert_fail ("End.isValid() && \"Declaration end location not nested within a known region\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 524, __extension__
 __PRETTY_FUNCTION__));
      EndFileID = SM.getFileID(End);
    }
  }
  SourceRegions.emplace_back(Counter(), Start, End);
}

/// Write the mapping data to the output stream
void write(llvm::raw_ostream &OS) {
  SmallVector<unsigned, 16> FileIDMapping;
  gatherFileIDs(FileIDMapping);
  emitSourceRegions(SourceRegionFilter());

  if (MappingRegions.empty())
    return;

  CoverageMappingWriter Writer(FileIDMapping, std::nullopt, MappingRegions);
  Writer.write(OS);
}
543};

545/// A StmtVisitor that creates coverage mapping regions which map
546/// from the source code locations to the PGO counters.
547struct CounterCoverageMappingBuilder
  : public CoverageMappingBuilder,
    public ConstStmtVisitor<CounterCoverageMappingBuilder> {
/// The map of statements to count values.
llvm::DenseMap<const Stmt *, unsigned> &CounterMap;

/// A stack of currently live regions.
std::vector<SourceMappingRegion> RegionStack;

CounterExpressionBuilder Builder;

/// A location in the most recently visited file or macro.
///
/// This is used to adjust the active source regions appropriately when
/// expressions cross file or macro boundaries.
SourceLocation MostRecentLocation;

/// Whether the visitor at a terminate statement.
bool HasTerminateStmt = false;

/// Gap region counter after terminate statement.
Counter GapRegionCounter;

/// Return a counter for the subtraction of \c RHS from \c LHS
Counter subtractCounters(Counter LHS, Counter RHS, bool Simplify = true) {
  return Builder.subtract(LHS, RHS, Simplify);
}

/// Return a counter for the sum of \c LHS and \c RHS.
Counter addCounters(Counter LHS, Counter RHS, bool Simplify = true) {
  return Builder.add(LHS, RHS, Simplify);
}

Counter addCounters(Counter C1, Counter C2, Counter C3,
                    bool Simplify = true) {
  return addCounters(addCounters(C1, C2, Simplify), C3, Simplify);
}

/// Return the region counter for the given statement.
///
/// This should only be called on statements that have a dedicated counter.
Counter getRegionCounter(const Stmt *S) {
  return Counter::getCounter(CounterMap[S]);
}

/// Push a region onto the stack.
///
/// Returns the index on the stack where the region was pushed. This can be
/// used with popRegions to exit a "scope", ending the region that was pushed.
size_t pushRegion(Counter Count,
                  std::optional<SourceLocation> StartLoc = std::nullopt,
                  std::optional<SourceLocation> EndLoc = std::nullopt,
                  std::optional<Counter> FalseCount = std::nullopt) {

  if (StartLoc && !FalseCount) {
    MostRecentLocation = *StartLoc;
  }

  // If either of these locations is invalid, something elsewhere in the
  // compiler has broken.
  assert((!StartLoc || StartLoc->isValid()) && "Start location is not valid")(static_cast <bool> ((!StartLoc || StartLoc->isValid
()) && "Start location is not valid") ? void (0) : __assert_fail
 ("(!StartLoc || StartLoc->isValid()) && \"Start location is not valid\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 607, __extension__
 __PRETTY_FUNCTION__));
  assert((!EndLoc || EndLoc->isValid()) && "End location is not valid")(static_cast <bool> ((!EndLoc || EndLoc->isValid()) &&
 "End location is not valid") ? void (0) : __assert_fail ("(!EndLoc || EndLoc->isValid()) && \"End location is not valid\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 608, __extension__
 __PRETTY_FUNCTION__));

  // However, we can still recover without crashing.
  // If either location is invalid, set it to std::nullopt to avoid
  // letting users of RegionStack think that region has a valid start/end
  // location.
  if (StartLoc && StartLoc->isInvalid())
    StartLoc = std::nullopt;
  if (EndLoc && EndLoc->isInvalid())
    EndLoc = std::nullopt;
  RegionStack.emplace_back(Count, FalseCount, StartLoc, EndLoc);

  return RegionStack.size() - 1;
}

size_t locationDepth(SourceLocation Loc) {
  size_t Depth = 0;
  while (Loc.isValid()) {
    Loc = getIncludeOrExpansionLoc(Loc);
    Depth++;
  }
  return Depth;
}

/// Pop regions from the stack into the function's list of regions.
///
/// Adds all regions from \c ParentIndex to the top of the stack to the
/// function's \c SourceRegions.
void popRegions(size_t ParentIndex) {
  assert(RegionStack.size() >= ParentIndex && "parent not in stack")(static_cast <bool> (RegionStack.size() >= ParentIndex
 && "parent not in stack") ? void (0) : __assert_fail
 ("RegionStack.size() >= ParentIndex && \"parent not in stack\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 637, __extension__
 __PRETTY_FUNCTION__));
  while (RegionStack.size() > ParentIndex) {
    SourceMappingRegion &Region = RegionStack.back();
    if (Region.hasStartLoc() &&
        (Region.hasEndLoc() || RegionStack[ParentIndex].hasEndLoc())) {
      SourceLocation StartLoc = Region.getBeginLoc();
      SourceLocation EndLoc = Region.hasEndLoc()
                                  ? Region.getEndLoc()
                                  : RegionStack[ParentIndex].getEndLoc();
      bool isBranch = Region.isBranch();
      size_t StartDepth = locationDepth(StartLoc);
      size_t EndDepth = locationDepth(EndLoc);
      while (!SM.isWrittenInSameFile(StartLoc, EndLoc)) {
        bool UnnestStart = StartDepth >= EndDepth;
        bool UnnestEnd = EndDepth >= StartDepth;
        if (UnnestEnd) {
          // The region ends in a nested file or macro expansion. If the
          // region is not a branch region, create a separate region for each
          // expansion, and for all regions, update the EndLoc. Branch
          // regions should not be split in order to keep a straightforward
          // correspondance between the region and its associated branch
          // condition, even if the condition spans multiple depths.
          SourceLocation NestedLoc = getStartOfFileOrMacro(EndLoc);
          assert(SM.isWrittenInSameFile(NestedLoc, EndLoc))(static_cast <bool> (SM.isWrittenInSameFile(NestedLoc, EndLoc
)) ? void (0) : __assert_fail ("SM.isWrittenInSameFile(NestedLoc, EndLoc)"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 660, __extension__
 __PRETTY_FUNCTION__));

          if (!isBranch && !isRegionAlreadyAdded(NestedLoc, EndLoc))
            SourceRegions.emplace_back(Region.getCounter(), NestedLoc,
                                       EndLoc);

          EndLoc = getPreciseTokenLocEnd(getIncludeOrExpansionLoc(EndLoc));
          if (EndLoc.isInvalid())
            llvm::report_fatal_error(
                "File exit not handled before popRegions");
          EndDepth--;
        }
        if (UnnestStart) {
          // The region ends in a nested file or macro expansion. If the
          // region is not a branch region, create a separate region for each
          // expansion, and for all regions, update the StartLoc. Branch
          // regions should not be split in order to keep a straightforward
          // correspondance between the region and its associated branch
          // condition, even if the condition spans multiple depths.
          SourceLocation NestedLoc = getEndOfFileOrMacro(StartLoc);
          assert(SM.isWrittenInSameFile(StartLoc, NestedLoc))(static_cast <bool> (SM.isWrittenInSameFile(StartLoc, NestedLoc
)) ? void (0) : __assert_fail ("SM.isWrittenInSameFile(StartLoc, NestedLoc)"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 680, __extension__
 __PRETTY_FUNCTION__));

          if (!isBranch && !isRegionAlreadyAdded(StartLoc, NestedLoc))
            SourceRegions.emplace_back(Region.getCounter(), StartLoc,
                                       NestedLoc);

          StartLoc = getIncludeOrExpansionLoc(StartLoc);
          if (StartLoc.isInvalid())
            llvm::report_fatal_error(
                "File exit not handled before popRegions");
          StartDepth--;
        }
      }
      Region.setStartLoc(StartLoc);
      Region.setEndLoc(EndLoc);

      if (!isBranch) {
        MostRecentLocation = EndLoc;
        // If this region happens to span an entire expansion, we need to
        // make sure we don't overlap the parent region with it.
        if (StartLoc == getStartOfFileOrMacro(StartLoc) &&
            EndLoc == getEndOfFileOrMacro(EndLoc))
          MostRecentLocation = getIncludeOrExpansionLoc(EndLoc);
      }

      assert(SM.isWrittenInSameFile(Region.getBeginLoc(), EndLoc))(static_cast <bool> (SM.isWrittenInSameFile(Region.getBeginLoc
(), EndLoc)) ? void (0) : __assert_fail ("SM.isWrittenInSameFile(Region.getBeginLoc(), EndLoc)"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 705, __extension__
 __PRETTY_FUNCTION__));
      assert(SpellingRegion(SM, Region).isInSourceOrder())(static_cast <bool> (SpellingRegion(SM, Region).isInSourceOrder
()) ? void (0) : __assert_fail ("SpellingRegion(SM, Region).isInSourceOrder()"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 706, __extension__
 __PRETTY_FUNCTION__));
      SourceRegions.push_back(Region);
    }
    RegionStack.pop_back();
  }
}

/// Return the currently active region.
SourceMappingRegion &getRegion() {
  assert(!RegionStack.empty() && "statement has no region")(static_cast <bool> (!RegionStack.empty() && "statement has no region"
) ? void (0) : __assert_fail ("!RegionStack.empty() && \"statement has no region\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 715, __extension__
 __PRETTY_FUNCTION__));
  return RegionStack.back();
}

/// Propagate counts through the children of \p S if \p VisitChildren is true.
/// Otherwise, only emit a count for \p S itself.
Counter propagateCounts(Counter TopCount, const Stmt *S,
                        bool VisitChildren = true) {
  SourceLocation StartLoc = getStart(S);
12
←
Passing null pointer value via 1st parameter 'S'→
13
←
Calling 'CoverageMappingBuilder::getStart'→
  SourceLocation EndLoc = getEnd(S);
  size_t Index = pushRegion(TopCount, StartLoc, EndLoc);
  if (VisitChildren)
    Visit(S);
  Counter ExitCount = getRegion().getCounter();
  popRegions(Index);

  // The statement may be spanned by an expansion. Make sure we handle a file
  // exit out of this expansion before moving to the next statement.
  if (SM.isBeforeInTranslationUnit(StartLoc, S->getBeginLoc()))
    MostRecentLocation = EndLoc;

  return ExitCount;
}

/// Determine whether the given condition can be constant folded.
bool ConditionFoldsToBool(const Expr *Cond) {
  Expr::EvalResult Result;
  return (Cond->EvaluateAsInt(Result, CVM.getCodeGenModule().getContext()));
}

/// Create a Branch Region around an instrumentable condition for coverage
/// and add it to the function's SourceRegions.  A branch region tracks a
/// "True" counter and a "False" counter for boolean expressions that
/// result in the generation of a branch.
void createBranchRegion(const Expr *C, Counter TrueCnt, Counter FalseCnt) {
  // Check for NULL conditions.
  if (!C)
    return;

  // Ensure we are an instrumentable condition (i.e. no "&&" or "||").  Push
  // region onto RegionStack but immediately pop it (which adds it to the
  // function's SourceRegions) because it doesn't apply to any other source
  // code other than the Condition.
  if (CodeGenFunction::isInstrumentedCondition(C)) {
    // If a condition can fold to true or false, the corresponding branch
    // will be removed.  Create a region with both counters hard-coded to
    // zero. This allows us to visualize them in a special way.
    // Alternatively, we can prevent any optimization done via
    // constant-folding by ensuring that ConstantFoldsToSimpleInteger() in
    // CodeGenFunction.c always returns false, but that is very heavy-handed.
    if (ConditionFoldsToBool(C))
      popRegions(pushRegion(Counter::getZero(), getStart(C), getEnd(C),
                            Counter::getZero()));
    else
      // Otherwise, create a region with the True counter and False counter.
      popRegions(pushRegion(TrueCnt, getStart(C), getEnd(C), FalseCnt));
  }
}

/// Create a Branch Region around a SwitchCase for code coverage
/// and add it to the function's SourceRegions.
void createSwitchCaseRegion(const SwitchCase *SC, Counter TrueCnt,
                            Counter FalseCnt) {
  // Push region onto RegionStack but immediately pop it (which adds it to
  // the function's SourceRegions) because it doesn't apply to any other
  // source other than the SwitchCase.
  popRegions(pushRegion(TrueCnt, getStart(SC), SC->getColonLoc(), FalseCnt));
}

/// Check whether a region with bounds \c StartLoc and \c EndLoc
/// is already added to \c SourceRegions.
bool isRegionAlreadyAdded(SourceLocation StartLoc, SourceLocation EndLoc,
                          bool isBranch = false) {
  return llvm::any_of(
      llvm::reverse(SourceRegions), [&](const SourceMappingRegion &Region) {
        return Region.getBeginLoc() == StartLoc &&
               Region.getEndLoc() == EndLoc && Region.isBranch() == isBranch;
      });
}

/// Adjust the most recently visited location to \c EndLoc.
///
/// This should be used after visiting any statements in non-source order.
void adjustForOutOfOrderTraversal(SourceLocation EndLoc) {
  MostRecentLocation = EndLoc;
  // The code region for a whole macro is created in handleFileExit() when
  // it detects exiting of the virtual file of that macro. If we visited
  // statements in non-source order, we might already have such a region
  // added, for example, if a body of a loop is divided among multiple
  // macros. Avoid adding duplicate regions in such case.
  if (getRegion().hasEndLoc() &&
      MostRecentLocation == getEndOfFileOrMacro(MostRecentLocation) &&
      isRegionAlreadyAdded(getStartOfFileOrMacro(MostRecentLocation),
                           MostRecentLocation, getRegion().isBranch()))
    MostRecentLocation = getIncludeOrExpansionLoc(MostRecentLocation);
}

/// Adjust regions and state when \c NewLoc exits a file.
///
/// If moving from our most recently tracked location to \c NewLoc exits any
/// files, this adjusts our current region stack and creates the file regions
/// for the exited file.
void handleFileExit(SourceLocation NewLoc) {
  if (NewLoc.isInvalid() ||
      SM.isWrittenInSameFile(MostRecentLocation, NewLoc))
    return;

  // If NewLoc is not in a file that contains MostRecentLocation, walk up to
  // find the common ancestor.
  SourceLocation LCA = NewLoc;
  FileID ParentFile = SM.getFileID(LCA);
  while (!isNestedIn(MostRecentLocation, ParentFile)) {
    LCA = getIncludeOrExpansionLoc(LCA);
    if (LCA.isInvalid() || SM.isWrittenInSameFile(LCA, MostRecentLocation)) {
      // Since there isn't a common ancestor, no file was exited. We just need
      // to adjust our location to the new file.
      MostRecentLocation = NewLoc;
      return;
    }
    ParentFile = SM.getFileID(LCA);
  }

  llvm::SmallSet<SourceLocation, 8> StartLocs;
  std::optional<Counter> ParentCounter;
  for (SourceMappingRegion &I : llvm::reverse(RegionStack)) {
    if (!I.hasStartLoc())
      continue;
    SourceLocation Loc = I.getBeginLoc();
    if (!isNestedIn(Loc, ParentFile)) {
      ParentCounter = I.getCounter();
      break;
    }

    while (!SM.isInFileID(Loc, ParentFile)) {
      // The most nested region for each start location is the one with the
      // correct count. We avoid creating redundant regions by stopping once
      // we've seen this region.
      if (StartLocs.insert(Loc).second) {
        if (I.isBranch())
          SourceRegions.emplace_back(I.getCounter(), I.getFalseCounter(), Loc,
                                     getEndOfFileOrMacro(Loc), I.isBranch());
        else
          SourceRegions.emplace_back(I.getCounter(), Loc,
                                     getEndOfFileOrMacro(Loc));
      }
      Loc = getIncludeOrExpansionLoc(Loc);
    }
    I.setStartLoc(getPreciseTokenLocEnd(Loc));
  }

  if (ParentCounter) {
    // If the file is contained completely by another region and doesn't
    // immediately start its own region, the whole file gets a region
    // corresponding to the parent.
    SourceLocation Loc = MostRecentLocation;
    while (isNestedIn(Loc, ParentFile)) {
      SourceLocation FileStart = getStartOfFileOrMacro(Loc);
      if (StartLocs.insert(FileStart).second) {
        SourceRegions.emplace_back(*ParentCounter, FileStart,
                                   getEndOfFileOrMacro(Loc));
        assert(SpellingRegion(SM, SourceRegions.back()).isInSourceOrder())(static_cast <bool> (SpellingRegion(SM, SourceRegions.back
()).isInSourceOrder()) ? void (0) : __assert_fail ("SpellingRegion(SM, SourceRegions.back()).isInSourceOrder()"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 875, __extension__
 __PRETTY_FUNCTION__));
      }
      Loc = getIncludeOrExpansionLoc(Loc);
    }
  }

  MostRecentLocation = NewLoc;
}

/// Ensure that \c S is included in the current region.
void extendRegion(const Stmt *S) {
  SourceMappingRegion &Region = getRegion();
  SourceLocation StartLoc = getStart(S);

  handleFileExit(StartLoc);
  if (!Region.hasStartLoc())
    Region.setStartLoc(StartLoc);
}

/// Mark \c S as a terminator, starting a zero region.
void terminateRegion(const Stmt *S) {
  extendRegion(S);
  SourceMappingRegion &Region = getRegion();
  SourceLocation EndLoc = getEnd(S);
  if (!Region.hasEndLoc())
    Region.setEndLoc(EndLoc);
  pushRegion(Counter::getZero());
  HasTerminateStmt = true;
}

/// Find a valid gap range between \p AfterLoc and \p BeforeLoc.
std::optional<SourceRange> findGapAreaBetween(SourceLocation AfterLoc,
                                              SourceLocation BeforeLoc) {
  // If AfterLoc is in function-like macro, use the right parenthesis
  // location.
  if (AfterLoc.isMacroID()) {
    FileID FID = SM.getFileID(AfterLoc);
    const SrcMgr::ExpansionInfo *EI = &SM.getSLocEntry(FID).getExpansion();
    if (EI->isFunctionMacroExpansion())
      AfterLoc = EI->getExpansionLocEnd();
  }

  size_t StartDepth = locationDepth(AfterLoc);
  size_t EndDepth = locationDepth(BeforeLoc);
  while (!SM.isWrittenInSameFile(AfterLoc, BeforeLoc)) {
    bool UnnestStart = StartDepth >= EndDepth;
    bool UnnestEnd = EndDepth >= StartDepth;
    if (UnnestEnd) {
      assert(SM.isWrittenInSameFile(getStartOfFileOrMacro(BeforeLoc),(static_cast <bool> (SM.isWrittenInSameFile(getStartOfFileOrMacro
(BeforeLoc), BeforeLoc)) ? void (0) : __assert_fail ("SM.isWrittenInSameFile(getStartOfFileOrMacro(BeforeLoc), BeforeLoc)"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 924, __extension__
 __PRETTY_FUNCTION__))
                                    BeforeLoc))(static_cast <bool> (SM.isWrittenInSameFile(getStartOfFileOrMacro
(BeforeLoc), BeforeLoc)) ? void (0) : __assert_fail ("SM.isWrittenInSameFile(getStartOfFileOrMacro(BeforeLoc), BeforeLoc)"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 924, __extension__
 __PRETTY_FUNCTION__));

      BeforeLoc = getIncludeOrExpansionLoc(BeforeLoc);
      assert(BeforeLoc.isValid())(static_cast <bool> (BeforeLoc.isValid()) ? void (0) : __assert_fail
 ("BeforeLoc.isValid()", "clang/lib/CodeGen/CoverageMappingGen.cpp"
, 927, __extension__ __PRETTY_FUNCTION__));
      EndDepth--;
    }
    if (UnnestStart) {
      assert(SM.isWrittenInSameFile(AfterLoc,(static_cast <bool> (SM.isWrittenInSameFile(AfterLoc, getEndOfFileOrMacro
(AfterLoc))) ? void (0) : __assert_fail ("SM.isWrittenInSameFile(AfterLoc, getEndOfFileOrMacro(AfterLoc))"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 932, __extension__
 __PRETTY_FUNCTION__))
                                    getEndOfFileOrMacro(AfterLoc)))(static_cast <bool> (SM.isWrittenInSameFile(AfterLoc, getEndOfFileOrMacro
(AfterLoc))) ? void (0) : __assert_fail ("SM.isWrittenInSameFile(AfterLoc, getEndOfFileOrMacro(AfterLoc))"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 932, __extension__
 __PRETTY_FUNCTION__));

      AfterLoc = getIncludeOrExpansionLoc(AfterLoc);
      assert(AfterLoc.isValid())(static_cast <bool> (AfterLoc.isValid()) ? void (0) : __assert_fail
 ("AfterLoc.isValid()", "clang/lib/CodeGen/CoverageMappingGen.cpp"
, 935, __extension__ __PRETTY_FUNCTION__));
      AfterLoc = getPreciseTokenLocEnd(AfterLoc);
      assert(AfterLoc.isValid())(static_cast <bool> (AfterLoc.isValid()) ? void (0) : __assert_fail
 ("AfterLoc.isValid()", "clang/lib/CodeGen/CoverageMappingGen.cpp"
, 937, __extension__ __PRETTY_FUNCTION__));
      StartDepth--;
    }
  }
  AfterLoc = getPreciseTokenLocEnd(AfterLoc);
  // If the start and end locations of the gap are both within the same macro
  // file, the range may not be in source order.
  if (AfterLoc.isMacroID() || BeforeLoc.isMacroID())
    return std::nullopt;
  if (!SM.isWrittenInSameFile(AfterLoc, BeforeLoc) ||
      !SpellingRegion(SM, AfterLoc, BeforeLoc).isInSourceOrder())
    return std::nullopt;
  return {{AfterLoc, BeforeLoc}};
}

/// Emit a gap region between \p StartLoc and \p EndLoc with the given count.
void fillGapAreaWithCount(SourceLocation StartLoc, SourceLocation EndLoc,
                          Counter Count) {
  if (StartLoc == EndLoc)
    return;
  assert(SpellingRegion(SM, StartLoc, EndLoc).isInSourceOrder())(static_cast <bool> (SpellingRegion(SM, StartLoc, EndLoc
).isInSourceOrder()) ? void (0) : __assert_fail ("SpellingRegion(SM, StartLoc, EndLoc).isInSourceOrder()"
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 957, __extension__
 __PRETTY_FUNCTION__));
  handleFileExit(StartLoc);
  size_t Index = pushRegion(Count, StartLoc, EndLoc);
  getRegion().setGap(true);
  handleFileExit(EndLoc);
  popRegions(Index);
}

/// Keep counts of breaks and continues inside loops.
struct BreakContinue {
  Counter BreakCount;
  Counter ContinueCount;
};
SmallVector<BreakContinue, 8> BreakContinueStack;

CounterCoverageMappingBuilder(
    CoverageMappingModuleGen &CVM,
    llvm::DenseMap<const Stmt *, unsigned> &CounterMap, SourceManager &SM,
    const LangOptions &LangOpts)
    : CoverageMappingBuilder(CVM, SM, LangOpts), CounterMap(CounterMap) {}

/// Write the mapping data to the output stream
void write(llvm::raw_ostream &OS) {
  llvm::SmallVector<unsigned, 8> VirtualFileMapping;
  gatherFileIDs(VirtualFileMapping);
  SourceRegionFilter Filter = emitExpansionRegions();
  emitSourceRegions(Filter);
  gatherSkippedRegions();

  if (MappingRegions.empty())
    return;

  CoverageMappingWriter Writer(VirtualFileMapping, Builder.getExpressions(),
                               MappingRegions);
  Writer.write(OS);
}

void VisitStmt(const Stmt *S) {
  if (S->getBeginLoc().isValid())
    extendRegion(S);
  const Stmt *LastStmt = nullptr;
  bool SaveTerminateStmt = HasTerminateStmt;
  HasTerminateStmt = false;
  GapRegionCounter = Counter::getZero();
  for (const Stmt *Child : S->children())
    if (Child) {
      // If last statement contains terminate statements, add a gap area
      // between the two statements. Skipping attributed statements, because
      // they don't have valid start location.
      if (LastStmt && HasTerminateStmt && !isa<AttributedStmt>(Child)) {
        auto Gap = findGapAreaBetween(getEnd(LastStmt), getStart(Child));
        if (Gap)
          fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(),
                               GapRegionCounter);
        SaveTerminateStmt = true;
        HasTerminateStmt = false;
      }
      this->Visit(Child);
      LastStmt = Child;
    }
  if (SaveTerminateStmt)
    HasTerminateStmt = true;
  handleFileExit(getEnd(S));
}

void VisitDecl(const Decl *D) {
  Stmt *Body = D->getBody();
4
←
'Body' initialized here→

  // Do not propagate region counts into system headers unless collecting
  // coverage from system headers is explicitly enabled.
  if (!SystemHeadersCoverage && Body &&
5
←
Assuming the condition is true→
6
←
Assuming pointer value is null→
7
←
Assuming 'Body' is null→
      SM.isInSystemHeader(SM.getSpellingLoc(getStart(Body))))
    return;

  // Do not visit the artificial children nodes of defaulted methods. The
  // lexer may not be able to report back precise token end locations for
  // these children nodes (llvm.org/PR39822), and moreover users will not be
  // able to see coverage for them.
  bool Defaulted = false;
  if (auto *Method8.1
'Method' is null
 = dyn_cast<CXXMethodDecl>(D))
8
←
Assuming 'D' is not a 'CastReturnType'→
9
←
Taking false branch→
    Defaulted = Method->isDefaulted();

  propagateCounts(getRegionCounter(Body), Body,
10
←
Passing null pointer value via 2nd parameter 'S'→
11
←
Calling 'CounterCoverageMappingBuilder::propagateCounts'→
                  /*VisitChildren=*/!Defaulted);
  assert(RegionStack.empty() && "Regions entered but never exited")(static_cast <bool> (RegionStack.empty() && "Regions entered but never exited"
) ? void (0) : __assert_fail ("RegionStack.empty() && \"Regions entered but never exited\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 1041, __extension__
 __PRETTY_FUNCTION__));
}

void VisitReturnStmt(const ReturnStmt *S) {
  extendRegion(S);
  if (S->getRetValue())
    Visit(S->getRetValue());
  terminateRegion(S);
}

void VisitCoroutineBodyStmt(const CoroutineBodyStmt *S) {
  extendRegion(S);
  Visit(S->getBody());
}

void VisitCoreturnStmt(const CoreturnStmt *S) {
  extendRegion(S);
  if (S->getOperand())
    Visit(S->getOperand());
  terminateRegion(S);
}

void VisitCXXThrowExpr(const CXXThrowExpr *E) {
  extendRegion(E);
  if (E->getSubExpr())
    Visit(E->getSubExpr());
  terminateRegion(E);
}

void VisitGotoStmt(const GotoStmt *S) { terminateRegion(S); }

void VisitLabelStmt(const LabelStmt *S) {
  Counter LabelCount = getRegionCounter(S);
  SourceLocation Start = getStart(S);
  // We can't extendRegion here or we risk overlapping with our new region.
  handleFileExit(Start);
  pushRegion(LabelCount, Start);
  Visit(S->getSubStmt());
}

void VisitBreakStmt(const BreakStmt *S) {
  assert(!BreakContinueStack.empty() && "break not in a loop or switch!")(static_cast <bool> (!BreakContinueStack.empty() &&
 "break not in a loop or switch!") ? void (0) : __assert_fail
 ("!BreakContinueStack.empty() && \"break not in a loop or switch!\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 1082, __extension__
 __PRETTY_FUNCTION__));
  BreakContinueStack.back().BreakCount = addCounters(
      BreakContinueStack.back().BreakCount, getRegion().getCounter());
  // FIXME: a break in a switch should terminate regions for all preceding
  // case statements, not just the most recent one.
  terminateRegion(S);
}

void VisitContinueStmt(const ContinueStmt *S) {
  assert(!BreakContinueStack.empty() && "continue stmt not in a loop!")(static_cast <bool> (!BreakContinueStack.empty() &&
 "continue stmt not in a loop!") ? void (0) : __assert_fail (
"!BreakContinueStack.empty() && \"continue stmt not in a loop!\""
, "clang/lib/CodeGen/CoverageMappingGen.cpp", 1091, __extension__
 __PRETTY_FUNCTION__));
  BreakContinueStack.back().ContinueCount = addCounters(
      BreakContinueStack.back().ContinueCount, getRegion().getCounter());
  terminateRegion(S);
}

void VisitCallExpr(const CallExpr *E) {
  VisitStmt(E);

  // Terminate the region when we hit a noreturn function.
  // (This is helpful dealing with switch statements.)
  QualType CalleeType = E->getCallee()->getType();
  if (getFunctionExtInfo(*CalleeType).getNoReturn())
    terminateRegion(E);
}

void VisitWhileStmt(const WhileStmt *S) {
  extendRegion(S);

  Counter ParentCount = getRegion().getCounter();
  Counter BodyCount = getRegionCounter(S);

  // Handle the body first so that we can get the backedge count.
  BreakContinueStack.push_back(BreakContinue());
  extendRegion(S->getBody());
  Counter BackedgeCount = propagateCounts(BodyCount, S->getBody());
  BreakContinue BC = BreakContinueStack.pop_back_val();

  bool BodyHasTerminateStmt = HasTerminateStmt;
  HasTerminateStmt = false;

  // Go back to handle the condition.
  Counter CondCount =
      addCounters(ParentCount, BackedgeCount, BC.ContinueCount);
  propagateCounts(CondCount, S->getCond());
  adjustForOutOfOrderTraversal(getEnd(S));

  // The body count applies to the area immediately after the increment.
  auto Gap = findGapAreaBetween(S->getRParenLoc(), getStart(S->getBody()));
  if (Gap)
    fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), BodyCount);

  Counter OutCount =
      addCounters(BC.BreakCount, subtractCounters(CondCount, BodyCount));
  if (OutCount != ParentCount) {
    pushRegion(OutCount);
    GapRegionCounter = OutCount;
    if (BodyHasTerminateStmt)
      HasTerminateStmt = true;
  }

  // Create Branch Region around condition.
  createBranchRegion(S->getCond(), BodyCount,
                     subtractCounters(CondCount, BodyCount));
}

void VisitDoStmt(const DoStmt *S) {
  extendRegion(S);

  Counter ParentCount = getRegion().getCounter();
  Counter BodyCount = getRegionCounter(S);

  BreakContinueStack.push_back(BreakContinue());
  extendRegion(S->getBody());
  Counter BackedgeCount =
      propagateCounts(addCounters(ParentCount, BodyCount), S->getBody());
  BreakContinue BC = BreakContinueStack.pop_back_val();

  bool BodyHasTerminateStmt = HasTerminateStmt;
  HasTerminateStmt = false;

  Counter CondCount = addCounters(BackedgeCount, BC.ContinueCount);
  propagateCounts(CondCount, S->getCond());

  Counter OutCount =
      addCounters(BC.BreakCount, subtractCounters(CondCount, BodyCount));
  if (OutCount != ParentCount) {
    pushRegion(OutCount);
    GapRegionCounter = OutCount;
  }

  // Create Branch Region around condition.
  createBranchRegion(S->getCond(), BodyCount,
                     subtractCounters(CondCount, BodyCount));

  if (BodyHasTerminateStmt)
    HasTerminateStmt = true;
}

void VisitForStmt(const ForStmt *S) {
  extendRegion(S);
  if (S->getInit())
    Visit(S->getInit());

  Counter ParentCount = getRegion().getCounter();
  Counter BodyCount = getRegionCounter(S);

  // The loop increment may contain a break or continue.
  if (S->getInc())
    BreakContinueStack.emplace_back();

  // Handle the body first so that we can get the backedge count.
  BreakContinueStack.emplace_back();
  extendRegion(S->getBody());
  Counter BackedgeCount = propagateCounts(BodyCount, S->getBody());
  BreakContinue BodyBC = BreakContinueStack.pop_back_val();

  bool BodyHasTerminateStmt = HasTerminateStmt;
  HasTerminateStmt = false;

  // The increment is essentially part of the body but it needs to include
  // the count for all the continue statements.
  BreakContinue IncrementBC;
  if (const Stmt *Inc = S->getInc()) {
    propagateCounts(addCounters(BackedgeCount, BodyBC.ContinueCount), Inc);
    IncrementBC = BreakContinueStack.pop_back_val();
  }

  // Go back to handle the condition.
  Counter CondCount = addCounters(
      addCounters(ParentCount, BackedgeCount, BodyBC.ContinueCount),
      IncrementBC.ContinueCount);
  if (const Expr *Cond = S->getCond()) {
    propagateCounts(CondCount, Cond);
    adjustForOutOfOrderTraversal(getEnd(S));
  }

  // The body count applies to the area immediately after the increment.
  auto Gap = findGapAreaBetween(S->getRParenLoc(), getStart(S->getBody()));
  if (Gap)
    fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), BodyCount);

  Counter OutCount = addCounters(BodyBC.BreakCount, IncrementBC.BreakCount,
                                 subtractCounters(CondCount, BodyCount));
  if (OutCount != ParentCount) {
    pushRegion(OutCount);
    GapRegionCounter = OutCount;
    if (BodyHasTerminateStmt)
      HasTerminateStmt = true;
  }

  // Create Branch Region around condition.
  createBranchRegion(S->getCond(), BodyCount,
                     subtractCounters(CondCount, BodyCount));
}

void VisitCXXForRangeStmt(const CXXForRangeStmt *S) {
  extendRegion(S);
  if (S->getInit())
    Visit(S->getInit());
  Visit(S->getLoopVarStmt());
  Visit(S->getRangeStmt());

  Counter ParentCount = getRegion().getCounter();
  Counter BodyCount = getRegionCounter(S);

  BreakContinueStack.push_back(BreakContinue());
  extendRegion(S->getBody());
  Counter BackedgeCount = propagateCounts(BodyCount, S->getBody());
  BreakContinue BC = BreakContinueStack.pop_back_val();

  bool BodyHasTerminateStmt = HasTerminateStmt;
  HasTerminateStmt = false;

  // The body count applies to the area immediately after the range.
  auto Gap = findGapAreaBetween(S->getRParenLoc(), getStart(S->getBody()));
  if (Gap)
    fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), BodyCount);

  Counter LoopCount =
      addCounters(ParentCount, BackedgeCount, BC.ContinueCount);
  Counter OutCount =
      addCounters(BC.BreakCount, subtractCounters(LoopCount, BodyCount));
  if (OutCount != ParentCount) {
    pushRegion(OutCount);
    GapRegionCounter = OutCount;
    if (BodyHasTerminateStmt)
      HasTerminateStmt = true;
  }

  // Create Branch Region around condition.
  createBranchRegion(S->getCond(), BodyCount,
                     subtractCounters(LoopCount, BodyCount));
}

void VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S) {
  extendRegion(S);
  Visit(S->getElement());

  Counter ParentCount = getRegion().getCounter();
  Counter BodyCount = getRegionCounter(S);

  BreakContinueStack.push_back(BreakContinue());
  extendRegion(S->getBody());
  Counter BackedgeCount = propagateCounts(BodyCount, S->getBody());
  BreakContinue BC = BreakContinueStack.pop_back_val();

  // The body count applies to the area immediately after the collection.
  auto Gap = findGapAreaBetween(S->getRParenLoc(), getStart(S->getBody()));
  if (Gap)
    fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), BodyCount);

  Counter LoopCount =
      addCounters(ParentCount, BackedgeCount, BC.ContinueCount);
  Counter OutCount =
      addCounters(BC.BreakCount, subtractCounters(LoopCount, BodyCount));
  if (OutCount != ParentCount) {
    pushRegion(OutCount);
    GapRegionCounter = OutCount;
  }
}

void VisitSwitchStmt(const SwitchStmt *S) {
  extendRegion(S);
  if (S->getInit())
    Visit(S->getInit());
  Visit(S->getCond());

  BreakContinueStack.push_back(BreakContinue());

  const Stmt *Body = S->getBody();
  extendRegion(Body);
  if (const auto *CS = dyn_cast<CompoundStmt>(Body)) {
    if (!CS->body_empty()) {
      // Make a region for the body of the switch.  If the body starts with
      // a case, that case will reuse this region; otherwise, this covers
      // the unreachable code at the beginning of the switch body.
      size_t Index = pushRegion(Counter::getZero(), getStart(CS));
      getRegion().setGap(true);
      Visit(Body);

      // Set the end for the body of the switch, if it isn't already set.
      for (size_t i = RegionStack.size(); i != Index; --i) {
        if (!RegionStack[i - 1].hasEndLoc())
          RegionStack[i - 1].setEndLoc(getEnd(CS->body_back()));
      }

      popRegions(Index);
    }
  } else
    propagateCounts(Counter::getZero(), Body);
  BreakContinue BC = BreakContinueStack.pop_back_val();

  if (!BreakContinueStack.empty())
    BreakContinueStack.back().ContinueCount = addCounters(
        BreakContinueStack.back().ContinueCount, BC.ContinueCount);

  Counter ParentCount = getRegion().getCounter();
  Counter ExitCount = getRegionCounter(S);
  SourceLocation ExitLoc = getEnd(S);
  pushRegion(ExitCount);
  GapRegionCounter = ExitCount;

  // Ensure that handleFileExit recognizes when the end location is located
  // in a different file.
  MostRecentLocation = getStart(S);
  handleFileExit(ExitLoc);

  // Create a Branch Region around each Case. Subtract the case's
  // counter from the Parent counter to track the "False" branch count.
  Counter CaseCountSum;
  bool HasDefaultCase = false;
  const SwitchCase *Case = S->getSwitchCaseList();
  for (; Case; Case = Case->getNextSwitchCase()) {
    HasDefaultCase = HasDefaultCase || isa<DefaultStmt>(Case);
    CaseCountSum =
        addCounters(CaseCountSum, getRegionCounter(Case), /*Simplify=*/false);
    createSwitchCaseRegion(
        Case, getRegionCounter(Case),
        subtractCounters(ParentCount, getRegionCounter(Case)));
  }
  // Simplify is skipped while building the counters above: it can get really
  // slow on top of switches with thousands of cases. Instead, trigger
  // simplification by adding zero to the last counter.
  CaseCountSum = addCounters(CaseCountSum, Counter::getZero());

  // If no explicit default case exists, create a branch region to represent
  // the hidden branch, which will be added later by the CodeGen. This region
  // will be associated with the switch statement's condition.
  if (!HasDefaultCase) {
    Counter DefaultTrue = subtractCounters(ParentCount, CaseCountSum);
    Counter DefaultFalse = subtractCounters(ParentCount, DefaultTrue);
    createBranchRegion(S->getCond(), DefaultTrue, DefaultFalse);
  }
}

void VisitSwitchCase(const SwitchCase *S) {
  extendRegion(S);

  SourceMappingRegion &Parent = getRegion();

  Counter Count = addCounters(Parent.getCounter(), getRegionCounter(S));
  // Reuse the existing region if it starts at our label. This is typical of
  // the first case in a switch.
  if (Parent.hasStartLoc() && Parent.getBeginLoc() == getStart(S))
    Parent.setCounter(Count);
  else
    pushRegion(Count, getStart(S));

  GapRegionCounter = Count;

  if (const auto *CS = dyn_cast<CaseStmt>(S)) {
    Visit(CS->getLHS());
    if (const Expr *RHS = CS->getRHS())
      Visit(RHS);
  }
  Visit(S->getSubStmt());
}

void VisitIfStmt(const IfStmt *S) {
  extendRegion(S);
  if (S->getInit())
    Visit(S->getInit());

  // Extend into the condition before we propagate through it below - this is
  // needed to handle macros that generate the "if" but not the condition.
  if (!S->isConsteval())
    extendRegion(S->getCond());

  Counter ParentCount = getRegion().getCounter();
  Counter ThenCount = getRegionCounter(S);

  if (!S->isConsteval()) {
    // Emitting a counter for the condition makes it easier to interpret the
    // counter for the body when looking at the coverage.
    propagateCounts(ParentCount, S->getCond());

    // The 'then' count applies to the area immediately after the condition.
    std::optional<SourceRange> Gap =
        findGapAreaBetween(S->getRParenLoc(), getStart(S->getThen()));
    if (Gap)
      fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), ThenCount);
  }

  extendRegion(S->getThen());
  Counter OutCount = propagateCounts(ThenCount, S->getThen());

  Counter ElseCount = subtractCounters(ParentCount, ThenCount);
  if (const Stmt *Else = S->getElse()) {
    bool ThenHasTerminateStmt = HasTerminateStmt;
    HasTerminateStmt = false;
    // The 'else' count applies to the area immediately after the 'then'.
    std::optional<SourceRange> Gap =
        findGapAreaBetween(getEnd(S->getThen()), getStart(Else));
    if (Gap)
      fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), ElseCount);
    extendRegion(Else);
    OutCount = addCounters(OutCount, propagateCounts(ElseCount, Else));

    if (ThenHasTerminateStmt)
      HasTerminateStmt = true;
  } else
    OutCount = addCounters(OutCount, ElseCount);

  if (OutCount != ParentCount) {
    pushRegion(OutCount);
    GapRegionCounter = OutCount;
  }

  if (!S->isConsteval()) {
    // Create Branch Region around condition.
    createBranchRegion(S->getCond(), ThenCount,
                       subtractCounters(ParentCount, ThenCount));
  }
}

void VisitCXXTryStmt(const CXXTryStmt *S) {
  extendRegion(S);
  // Handle macros that generate the "try" but not the rest.
  extendRegion(S->getTryBlock());

  Counter ParentCount = getRegion().getCounter();
  propagateCounts(ParentCount, S->getTryBlock());

  for (unsigned I = 0, E = S->getNumHandlers(); I < E; ++I)
    Visit(S->getHandler(I));

  Counter ExitCount = getRegionCounter(S);
  pushRegion(ExitCount);
}

void VisitCXXCatchStmt(const CXXCatchStmt *S) {
  propagateCounts(getRegionCounter(S), S->getHandlerBlock());
}

void VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
  extendRegion(E);

  Counter ParentCount = getRegion().getCounter();
  Counter TrueCount = getRegionCounter(E);

  propagateCounts(ParentCount, E->getCond());
  Counter OutCount;

  if (!isa<BinaryConditionalOperator>(E)) {
    // The 'then' count applies to the area immediately after the condition.
    auto Gap =
        findGapAreaBetween(E->getQuestionLoc(), getStart(E->getTrueExpr()));
    if (Gap)
      fillGapAreaWithCount(Gap->getBegin(), Gap->getEnd(), TrueCount);

    extendRegion(E->getTrueExpr());
    OutCount = propagateCounts(TrueCount, E->getTrueExpr());
  }

  extendRegion(E->getFalseExpr());
  OutCount = addCounters(
      OutCount, propagateCounts(subtractCounters(ParentCount, TrueCount),
                                E->getFalseExpr()));

  if (OutCount != ParentCount) {
    pushRegion(OutCount);
    GapRegionCounter = OutCount;
  }

  // Create Branch Region around condition.
  createBranchRegion(E->getCond(), TrueCount,
                     subtractCounters(ParentCount, TrueCount));
}

void VisitBinLAnd(const BinaryOperator *E) {
  extendRegion(E->getLHS());
  propagateCounts(getRegion().getCounter(), E->getLHS());
  handleFileExit(getEnd(E->getLHS()));

  // Counter tracks the right hand side of a logical and operator.
  extendRegion(E->getRHS());
  propagateCounts(getRegionCounter(E), E->getRHS());

  // Extract the RHS's Execution Counter.
  Counter RHSExecCnt = getRegionCounter(E);

  // Extract the RHS's "True" Instance Counter.
  Counter RHSTrueCnt = getRegionCounter(E->getRHS());

  // Extract the Parent Region Counter.
  Counter ParentCnt = getRegion().getCounter();

  // Create Branch Region around LHS condition.
  createBranchRegion(E->getLHS(), RHSExecCnt,
                     subtractCounters(ParentCnt, RHSExecCnt));

  // Create Branch Region around RHS condition.
  createBranchRegion(E->getRHS(), RHSTrueCnt,
                     subtractCounters(RHSExecCnt, RHSTrueCnt));
}

// Determine whether the right side of OR operation need to be visited.
bool shouldVisitRHS(const Expr *LHS) {
  bool LHSIsTrue = false;
  bool LHSIsConst = false;
  if (!LHS->isValueDependent())
    LHSIsConst = LHS->EvaluateAsBooleanCondition(
        LHSIsTrue, CVM.getCodeGenModule().getContext());
  return !LHSIsConst || (LHSIsConst && !LHSIsTrue);
}

void VisitBinLOr(const BinaryOperator *E) {
  extendRegion(E->getLHS());
  Counter OutCount = propagateCounts(getRegion().getCounter(), E->getLHS());
  handleFileExit(getEnd(E->getLHS()));

  // Counter tracks the right hand side of a logical or operator.
  extendRegion(E->getRHS());
  propagateCounts(getRegionCounter(E), E->getRHS());

  // Extract the RHS's Execution Counter.
  Counter RHSExecCnt = getRegionCounter(E);

  // Extract the RHS's "False" Instance Counter.
  Counter RHSFalseCnt = getRegionCounter(E->getRHS());

  if (!shouldVisitRHS(E->getLHS())) {
    GapRegionCounter = OutCount;
  }

  // Extract the Parent Region Counter.
  Counter ParentCnt = getRegion().getCounter();

  // Create Branch Region around LHS condition.
  createBranchRegion(E->getLHS(), subtractCounters(ParentCnt, RHSExecCnt),
                     RHSExecCnt);

  // Create Branch Region around RHS condition.
  createBranchRegion(E->getRHS(), subtractCounters(RHSExecCnt, RHSFalseCnt),
                     RHSFalseCnt);
}

void VisitLambdaExpr(const LambdaExpr *LE) {
  // Lambdas are treated as their own functions for now, so we shouldn't
  // propagate counts into them.
}

void VisitPseudoObjectExpr(const PseudoObjectExpr *POE) {
  // Just visit syntatic expression as this is what users actually write.
  VisitStmt(POE->getSyntacticForm());
}

void VisitOpaqueValueExpr(const OpaqueValueExpr* OVE) {
  Visit(OVE->getSourceExpr());
}
1592};

1594} // end anonymous namespace

1596static void dump(llvm::raw_ostream &OS, StringRef FunctionName,
               ArrayRef<CounterExpression> Expressions,
               ArrayRef<CounterMappingRegion> Regions) {
OS << FunctionName << ":\n";
CounterMappingContext Ctx(Expressions);
for (const auto &R : Regions) {
  OS.indent(2);
  switch (R.Kind) {
  case CounterMappingRegion::CodeRegion:
    break;
  case CounterMappingRegion::ExpansionRegion:
    OS << "Expansion,";
    break;
  case CounterMappingRegion::SkippedRegion:
    OS << "Skipped,";
    break;
  case CounterMappingRegion::GapRegion:
    OS << "Gap,";
    break;
  case CounterMappingRegion::BranchRegion:
    OS << "Branch,";
    break;
  }

  OS << "File " << R.FileID << ", " << R.LineStart << ":" << R.ColumnStart
     << " -> " << R.LineEnd << ":" << R.ColumnEnd << " = ";
  Ctx.dump(R.Count, OS);

  if (R.Kind == CounterMappingRegion::BranchRegion) {
    OS << ", ";
    Ctx.dump(R.FalseCount, OS);
  }

  if (R.Kind == CounterMappingRegion::ExpansionRegion)
    OS << " (Expanded file = " << R.ExpandedFileID << ")";
  OS << "\n";
}
1633}

1635CoverageMappingModuleGen::CoverageMappingModuleGen(
  CodeGenModule &CGM, CoverageSourceInfo &SourceInfo)
  : CGM(CGM), SourceInfo(SourceInfo) {}

1639std::string CoverageMappingModuleGen::getCurrentDirname() {
if (!CGM.getCodeGenOpts().CoverageCompilationDir.empty())
  return CGM.getCodeGenOpts().CoverageCompilationDir;

SmallString<256> CWD;
llvm::sys::fs::current_path(CWD);
return CWD.str().str();
1646}

1648std::string CoverageMappingModuleGen::normalizeFilename(StringRef Filename) {
llvm::SmallString<256> Path(Filename);
llvm::sys::path::remove_dots(Path, /*remove_dot_dot=*/true);

/// Traverse coverage prefix map in reverse order because prefix replacements
/// are applied in reverse order starting from the last one when multiple
/// prefix replacement options are provided.
for (const auto &[From, To] :
     llvm::reverse(CGM.getCodeGenOpts().CoveragePrefixMap)) {
  if (llvm::sys::path::replace_path_prefix(Path, From, To))
    break;
}
return Path.str().str();
1661}

1663static std::string getInstrProfSection(const CodeGenModule &CGM,
                                     llvm::InstrProfSectKind SK) {
return llvm::getInstrProfSectionName(
    SK, CGM.getContext().getTargetInfo().getTriple().getObjectFormat());
1667}

1669void CoverageMappingModuleGen::emitFunctionMappingRecord(
  const FunctionInfo &Info, uint64_t FilenamesRef) {
llvm::LLVMContext &Ctx = CGM.getLLVMContext();

// Assign a name to the function record. This is used to merge duplicates.
std::string FuncRecordName = "__covrec_" + llvm::utohexstr(Info.NameHash);

// A dummy description for a function included-but-not-used in a TU can be
// replaced by full description provided by a different TU. The two kinds of
// descriptions play distinct roles: therefore, assign them different names
// to prevent `linkonce_odr` merging.
if (Info.IsUsed)
  FuncRecordName += "u";

// Create the function record type.
const uint64_t NameHash = Info.NameHash;
const uint64_t FuncHash = Info.FuncHash;
const std::string &CoverageMapping = Info.CoverageMapping;
1687#define COVMAP_FUNC_RECORD(Type, LLVMType, Name, Init) LLVMType,
llvm::Type *FunctionRecordTypes[] = {
1689#include "llvm/ProfileData/InstrProfData.inc"
};
auto *FunctionRecordTy =
    llvm::StructType::get(Ctx, ArrayRef(FunctionRecordTypes),
                          /*isPacked=*/true);

// Create the function record constant.
1696#define COVMAP_FUNC_RECORD(Type, LLVMType, Name, Init) Init,
llvm::Constant *FunctionRecordVals[] = {
    #include "llvm/ProfileData/InstrProfData.inc"
};
auto *FuncRecordConstant =
    llvm::ConstantStruct::get(FunctionRecordTy, ArrayRef(FunctionRecordVals));

// Create the function record global.
auto *FuncRecord = new llvm::GlobalVariable(
    CGM.getModule(), FunctionRecordTy, /*isConstant=*/true,
    llvm::GlobalValue::LinkOnceODRLinkage, FuncRecordConstant,
    FuncRecordName);
FuncRecord->setVisibility(llvm::GlobalValue::HiddenVisibility);
FuncRecord->setSection(getInstrProfSection(CGM, llvm::IPSK_covfun));
FuncRecord->setAlignment(llvm::Align(8));
if (CGM.supportsCOMDAT())
  FuncRecord->setComdat(CGM.getModule().getOrInsertComdat(FuncRecordName));

// Make sure the data doesn't get deleted.
CGM.addUsedGlobal(FuncRecord);
1716}

1718void CoverageMappingModuleGen::addFunctionMappingRecord(
  llvm::GlobalVariable *NamePtr, StringRef NameValue, uint64_t FuncHash,
  const std::string &CoverageMapping, bool IsUsed) {
llvm::LLVMContext &Ctx = CGM.getLLVMContext();
const uint64_t NameHash = llvm::IndexedInstrProf::ComputeHash(NameValue);
FunctionRecords.push_back({NameHash, FuncHash, CoverageMapping, IsUsed});

if (!IsUsed)
  FunctionNames.push_back(
      llvm::ConstantExpr::getBitCast(NamePtr, llvm::Type::getInt8PtrTy(Ctx)));

if (CGM.getCodeGenOpts().DumpCoverageMapping) {
  // Dump the coverage mapping data for this function by decoding the
  // encoded data. This allows us to dump the mapping regions which were
  // also processed by the CoverageMappingWriter which performs
  // additional minimization operations such as reducing the number of
  // expressions.
  llvm::SmallVector<std::string, 16> FilenameStrs;
  std::vector<StringRef> Filenames;
  std::vector<CounterExpression> Expressions;
  std::vector<CounterMappingRegion> Regions;
  FilenameStrs.resize(FileEntries.size() + 1);
  FilenameStrs[0] = normalizeFilename(getCurrentDirname());
  for (const auto &Entry : FileEntries) {
    auto I = Entry.second;
    FilenameStrs[I] = normalizeFilename(Entry.first->getName());
  }
  ArrayRef<std::string> FilenameRefs = llvm::ArrayRef(FilenameStrs);
  RawCoverageMappingReader Reader(CoverageMapping, FilenameRefs, Filenames,
                                  Expressions, Regions);
  if (Reader.read())
    return;
  dump(llvm::outs(), NameValue, Expressions, Regions);
}
1752}

1754void CoverageMappingModuleGen::emit() {
if (FunctionRecords.empty())
  return;
llvm::LLVMContext &Ctx = CGM.getLLVMContext();
auto *Int32Ty = llvm::Type::getInt32Ty(Ctx);

// Create the filenames and merge them with coverage mappings
llvm::SmallVector<std::string, 16> FilenameStrs;
FilenameStrs.resize(FileEntries.size() + 1);
// The first filename is the current working directory.
FilenameStrs[0] = normalizeFilename(getCurrentDirname());
for (const auto &Entry : FileEntries) {
  auto I = Entry.second;
  FilenameStrs[I] = normalizeFilename(Entry.first->getName());
}

std::string Filenames;
{
  llvm::raw_string_ostream OS(Filenames);
  CoverageFilenamesSectionWriter(FilenameStrs).write(OS);
}
auto *FilenamesVal =
    llvm::ConstantDataArray::getString(Ctx, Filenames, false);
const int64_t FilenamesRef = llvm::IndexedInstrProf::ComputeHash(Filenames);

// Emit the function records.
for (const FunctionInfo &Info : FunctionRecords)
  emitFunctionMappingRecord(Info, FilenamesRef);

const unsigned NRecords = 0;
const size_t FilenamesSize = Filenames.size();
const unsigned CoverageMappingSize = 0;
llvm::Type *CovDataHeaderTypes[] = {
1787#define COVMAP_HEADER(Type, LLVMType, Name, Init) LLVMType,
1788#include "llvm/ProfileData/InstrProfData.inc"
};
auto CovDataHeaderTy =
    llvm::StructType::get(Ctx, ArrayRef(CovDataHeaderTypes));
llvm::Constant *CovDataHeaderVals[] = {
1793#define COVMAP_HEADER(Type, LLVMType, Name, Init) Init,
1794#include "llvm/ProfileData/InstrProfData.inc"
};
auto CovDataHeaderVal =
    llvm::ConstantStruct::get(CovDataHeaderTy, ArrayRef(CovDataHeaderVals));

// Create the coverage data record
llvm::Type *CovDataTypes[] = {CovDataHeaderTy, FilenamesVal->getType()};
auto CovDataTy = llvm::StructType::get(Ctx, ArrayRef(CovDataTypes));
llvm::Constant *TUDataVals[] = {CovDataHeaderVal, FilenamesVal};
auto CovDataVal = llvm::ConstantStruct::get(CovDataTy, ArrayRef(TUDataVals));
auto CovData = new llvm::GlobalVariable(
    CGM.getModule(), CovDataTy, true, llvm::GlobalValue::PrivateLinkage,
    CovDataVal, llvm::getCoverageMappingVarName());

CovData->setSection(getInstrProfSection(CGM, llvm::IPSK_covmap));
CovData->setAlignment(llvm::Align(8));

// Make sure the data doesn't get deleted.
CGM.addUsedGlobal(CovData);
// Create the deferred function records array
if (!FunctionNames.empty()) {
  auto NamesArrTy = llvm::ArrayType::get(llvm::Type::getInt8PtrTy(Ctx),
                                         FunctionNames.size());
  auto NamesArrVal = llvm::ConstantArray::get(NamesArrTy, FunctionNames);
  // This variable will *NOT* be emitted to the object file. It is used
  // to pass the list of names referenced to codegen.
  new llvm::GlobalVariable(CGM.getModule(), NamesArrTy, true,
                           llvm::GlobalValue::InternalLinkage, NamesArrVal,
                           llvm::getCoverageUnusedNamesVarName());
}
1824}

1826unsigned CoverageMappingModuleGen::getFileID(const FileEntry *File) {
auto It = FileEntries.find(File);
if (It != FileEntries.end())
  return It->second;
unsigned FileID = FileEntries.size() + 1;
FileEntries.insert(std::make_pair(File, FileID));
return FileID;
1833}

1835void CoverageMappingGen::emitCounterMapping(const Decl *D,
                                          llvm::raw_ostream &OS) {
assert(CounterMap)(static_cast <bool> (CounterMap) ? void (0) : __assert_fail
 ("CounterMap", "clang/lib/CodeGen/CoverageMappingGen.cpp", 1837
, __extension__ __PRETTY_FUNCTION__));
1
Assuming field 'CounterMap' is non-null→
2
←
'?' condition is true→
CounterCoverageMappingBuilder Walker(CVM, *CounterMap, SM, LangOpts);
Walker.VisitDecl(D);
3
←
Calling 'CounterCoverageMappingBuilder::VisitDecl'→
Walker.write(OS);
1841}

1843void CoverageMappingGen::emitEmptyMapping(const Decl *D,
                                        llvm::raw_ostream &OS) {
EmptyCoverageMappingBuilder Walker(CVM, SM, LangOpts);
Walker.VisitDecl(D);
Walker.write(OS);
1848}