C++ SmallString::begin方法代码示例

/// EmitStringTable - If the current symbol table is non-empty, emit the string
/// table for it
void ELFWriter::EmitStringTable(const std::string &ModuleName) {
  if (!SymbolList.size()) return;  // Empty symbol table.
  ELFSection &StrTab = getStringTableSection();

  // Set the zero'th symbol to a null byte, as required.
  StrTab.emitByte(0);

  // Walk on the symbol list and write symbol names into the string table.
  unsigned Index = 1;
  for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
    ELFSym &Sym = *(*I);

    std::string Name;
    if (Sym.isGlobalValue()) {
      SmallString<40> NameStr;
      Mang->getNameWithPrefix(NameStr, Sym.getGlobalValue(), false);
      Name.append(NameStr.begin(), NameStr.end());
    } else if (Sym.isExternalSym())
      Name.append(Sym.getExternalSymbol());
    else if (Sym.isFileType())
      Name.append(ModuleName);

    if (Name.empty()) {
      Sym.NameIdx = 0;
    } else {
      Sym.NameIdx = Index;
      StrTab.emitString(Name);

      // Keep track of the number of bytes emitted to this section.
      Index += Name.size()+1;
    }
  }
  assert(Index == StrTab.size());
  StrTab.Size = Index;
}

// Compute the relative path from From to To.
static std::string computeRelativePath(StringRef From, StringRef To) {
  if (sys::path::is_absolute(From) || sys::path::is_absolute(To))
    return To;

  StringRef DirFrom = sys::path::parent_path(From);
  auto FromI = sys::path::begin(DirFrom);
  auto ToI = sys::path::begin(To);
  while (*FromI == *ToI) {
    ++FromI;
    ++ToI;
  }

  SmallString<128> Relative;
  for (auto FromE = sys::path::end(DirFrom); FromI != FromE; ++FromI)
    sys::path::append(Relative, "..");

  for (auto ToE = sys::path::end(To); ToI != ToE; ++ToI)
    sys::path::append(Relative, *ToI);

#ifdef LLVM_ON_WIN32
  // Replace backslashes with slashes so that the path is portable between *nix
  // and Windows.
  std::replace(Relative.begin(), Relative.end(), '\\', '/');
#endif

  return Relative.str();
}

// Convert a path into the canonical form.
// Canonical form is either "/", or "/segment" * N:
//   C:\foo\bar --> /c:/foo/bar
//   /foo/      --> /foo
//   a/b/c      --> /a/b/c
static SmallString<128> canonicalize(StringRef Path) {
  SmallString<128> Result = Path.rtrim('/');
  native(Result, sys::path::Style::posix);
  if (Result.empty() || Result.front() != '/')
    Result.insert(Result.begin(), '/');
  return Result;
}

void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
  MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());

  SmallString<128> Code;
  raw_svector_ostream VecOS(Code);
  getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
  VecOS.flush();
  IF->getCode().append(Code.begin(), Code.end());
}

void MCELFStreamer::EmitInstToData(const MCInst &Inst) {
  MCAssembler &Assembler = getAssembler();
  SmallVector<MCFixup, 4> Fixups;
  SmallString<256> Code;
  raw_svector_ostream VecOS(Code);
  Assembler.getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
  VecOS.flush();

  for (unsigned i = 0, e = Fixups.size(); i != e; ++i)
    fixSymbolsInTLSFixups(Fixups[i].getValue());

  // There are several possibilities here:
  //
  // If bundling is disabled, append the encoded instruction to the current data
  // fragment (or create a new such fragment if the current fragment is not a
  // data fragment).
  //
  // If bundling is enabled:
  // - If we're not in a bundle-locked group, emit the instruction into a data
  //   fragment of its own.
  // - If we're in a bundle-locked group, append the instruction to the current
  //   data fragment because we want all the instructions in a group to get into
  //   the same fragment. Be careful not to do that for the first instruction in
  //   the group, though.
  MCDataFragment *DF;

  if (Assembler.isBundlingEnabled()) {
    MCSectionData *SD = getCurrentSectionData();
    if (SD->isBundleLocked() && !SD->isBundleGroupBeforeFirstInst())
      DF = getOrCreateDataFragment();
    else {
      DF = new MCDataFragment(SD);
      if (SD->getBundleLockState() == MCSectionData::BundleLockedAlignToEnd) {
        // If this is a new fragment created for a bundle-locked group, and the
        // group was marked as "align_to_end", set a flag in the fragment.
        DF->setAlignToBundleEnd(true);
      }
    }

    // We're now emitting an instruction in a bundle group, so this flag has
    // to be turned off.
    SD->setBundleGroupBeforeFirstInst(false);
  } else {
    DF = getOrCreateDataFragment();
  }

  // Add the fixups and data.
  for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
    Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
    DF->getFixups().push_back(Fixups[i]);
  }
  DF->setHasInstructions(true);
  DF->getContents().append(Code.begin(), Code.end());
}

void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
  // Always create a new, separate fragment here, because its size can change
  // during relaxation.
  MCRelaxableFragment *IF = new MCRelaxableFragment(Inst);
  insert(IF);

  SmallString<128> Code;
  raw_svector_ostream VecOS(Code);
  getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
  VecOS.flush();
  IF->getContents().append(Code.begin(), Code.end());
}

StoredDiagnostic::StoredDiagnostic(DiagnosticsEngine::Level Level,
                                   const Diagnostic &Info)
  : ID(Info.getID()), Level(Level)
{
  assert((Info.getLocation().isInvalid() || Info.hasSourceManager()) &&
       "Valid source location without setting a source manager for diagnostic");
  if (Info.getLocation().isValid())
    Loc = FullSourceLoc(Info.getLocation(), Info.getSourceManager());
  SmallString<64> Message;
  Info.FormatDiagnostic(Message);
  this->Message.assign(Message.begin(), Message.end());
  this->Ranges.assign(Info.getRanges().begin(), Info.getRanges().end());
  this->FixIts.assign(Info.getFixItHints().begin(), Info.getFixItHints().end());
}

void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst,
                                          const MCSubtargetInfo &STI) {
  if (getAssembler().getRelaxAll() && getAssembler().isBundlingEnabled())
    llvm_unreachable("All instructions should have already been relaxed");

  // Always create a new, separate fragment here, because its size can change
  // during relaxation.
  MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI);
  insert(IF);

  SmallString<128> Code;
  raw_svector_ostream VecOS(Code);
  getAssembler().getEmitter().encodeInstruction(Inst, VecOS, IF->getFixups(),
                                                STI);
  IF->getContents().append(Code.begin(), Code.end());
}

void MCMachOStreamer::EmitInstToData(const MCInst &Inst,
                                     const MCSubtargetInfo &STI) {
  MCDataFragment *DF = getOrCreateDataFragment();

  SmallVector<MCFixup, 4> Fixups;
  SmallString<256> Code;
  raw_svector_ostream VecOS(Code);
  getAssembler().getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);

  // Add the fixups and data.
  for (MCFixup &Fixup : Fixups) {
    Fixup.setOffset(Fixup.getOffset() + DF->getContents().size());
    DF->getFixups().push_back(Fixup);
  }
  DF->getContents().append(Code.begin(), Code.end());
}

void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
  MCDataFragment *DF = getOrCreateDataFragment();

  SmallVector<MCFixup, 4> Fixups;
  SmallString<256> Code;
  raw_svector_ostream VecOS(Code);
  getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
  VecOS.flush();

  // Add the fixups and data.
  for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
    Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
    DF->addFixup(Fixups[i]);
  }
  DF->getContents().append(Code.begin(), Code.end());
}

HeaderSearch::LoadModuleMapResult 
HeaderSearch::loadModuleMapFile(const DirectoryEntry *Dir) {
  llvm::DenseMap<const DirectoryEntry *, bool>::iterator KnownDir
    = DirectoryHasModuleMap.find(Dir);
  if (KnownDir != DirectoryHasModuleMap.end())
    return KnownDir->second? LMM_AlreadyLoaded : LMM_InvalidModuleMap;
  
  SmallString<128> ModuleMapFileName;
  ModuleMapFileName += Dir->getName();
  unsigned ModuleMapDirNameLen = ModuleMapFileName.size();
  llvm::sys::path::append(ModuleMapFileName, "module.map");
  if (const FileEntry *ModuleMapFile = FileMgr.getFile(ModuleMapFileName)) {
    // We have found a module map file. Try to parse it.
    if (ModMap.parseModuleMapFile(ModuleMapFile)) {
      // No suitable module map.
      DirectoryHasModuleMap[Dir] = false;
      return LMM_InvalidModuleMap;
    }

    // This directory has a module map.
    DirectoryHasModuleMap[Dir] = true;
    
    // Check whether there is a private module map that we need to load as well.
    ModuleMapFileName.erase(ModuleMapFileName.begin() + ModuleMapDirNameLen,
                            ModuleMapFileName.end());
    llvm::sys::path::append(ModuleMapFileName, "module_private.map");
    if (const FileEntry *PrivateModuleMapFile
                                        = FileMgr.getFile(ModuleMapFileName)) {
      if (ModMap.parseModuleMapFile(PrivateModuleMapFile)) {
        // No suitable module map.
        DirectoryHasModuleMap[Dir] = false;
        return LMM_InvalidModuleMap;
      }      
    }
    
    return LMM_NewlyLoaded;
  }
  
  // No suitable module map.
  DirectoryHasModuleMap[Dir] = false;
  return LMM_InvalidModuleMap;
}

StoredDiagnostic::StoredDiagnostic(DiagnosticsEngine::Level Level,
                                   const Diagnostic &Info)
    : ID(Info.getID()), Level(Level)
{
    assert((Info.getLocation().isInvalid() || Info.hasSourceManager()) &&
           "Valid source location without setting a source manager for diagnostic");
    if (Info.getLocation().isValid())
        Loc = FullSourceLoc(Info.getLocation(), Info.getSourceManager());
    SmallString<64> Message;
    Info.FormatDiagnostic(Message);
    this->Message.assign(Message.begin(), Message.end());

    Ranges.reserve(Info.getNumRanges());
    for (unsigned I = 0, N = Info.getNumRanges(); I != N; ++I)
        Ranges.push_back(Info.getRange(I));

    FixIts.reserve(Info.getNumFixItHints());
    for (unsigned I = 0, N = Info.getNumFixItHints(); I != N; ++I)
        FixIts.push_back(Info.getFixItHint(I));
}

void MCELFStreamer::mergeFragment(MCDataFragment *DF,
                                  MCEncodedFragmentWithFixups *EF) {
  MCAssembler &Assembler = getAssembler();

  if (Assembler.isBundlingEnabled() && Assembler.getRelaxAll()) {
    uint64_t FSize = EF->getContents().size();

    if (FSize > Assembler.getBundleAlignSize())
      report_fatal_error("Fragment can't be larger than a bundle size");

    uint64_t RequiredBundlePadding = computeBundlePadding(
        Assembler, EF, DF->getContents().size(), FSize);

    if (RequiredBundlePadding > UINT8_MAX)
      report_fatal_error("Padding cannot exceed 255 bytes");

    if (RequiredBundlePadding > 0) {
      SmallString<256> Code;
      raw_svector_ostream VecOS(Code);
      MCObjectWriter *OW = Assembler.getBackend().createObjectWriter(VecOS);

      EF->setBundlePadding(static_cast<uint8_t>(RequiredBundlePadding));

      Assembler.writeFragmentPadding(*EF, FSize, OW);
      VecOS.flush();
      delete OW;

      DF->getContents().append(Code.begin(), Code.end());
    }
  }

  flushPendingLabels(DF, DF->getContents().size());

  for (unsigned i = 0, e = EF->getFixups().size(); i != e; ++i) {
    EF->getFixups()[i].setOffset(EF->getFixups()[i].getOffset() +
                                 DF->getContents().size());
    DF->getFixups().push_back(EF->getFixups()[i]);
  }
  DF->setHasInstructions(true);
  DF->getContents().append(EF->getContents().begin(), EF->getContents().end());
}

/// ComputeSymbolTable - Compute the symbol table data
///
/// \param StringTable [out] - The string table data.
/// \param StringIndexMap [out] - Map from symbol names to offsets in the
/// string table.
void MachObjectWriter::
ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable,
                   std::vector<MachSymbolData> &LocalSymbolData,
                   std::vector<MachSymbolData> &ExternalSymbolData,
                   std::vector<MachSymbolData> &UndefinedSymbolData) {
  // Build section lookup table.
  DenseMap<const MCSection*, uint8_t> SectionIndexMap;
  unsigned Index = 1;
  for (MCAssembler::iterator it = Asm.begin(),
         ie = Asm.end(); it != ie; ++it, ++Index)
    SectionIndexMap[&it->getSection()] = Index;
  assert(Index <= 256 && "Too many sections!");

  // Index 0 is always the empty string.
  StringMap<uint64_t> StringIndexMap;
  StringTable += '\x00';

  // Build the symbol arrays and the string table, but only for non-local
  // symbols.
  //
  // The particular order that we collect the symbols and create the string
  // table, then sort the symbols is chosen to match 'as'. Even though it
  // doesn't matter for correctness, this is important for letting us diff .o
  // files.
  for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
         ie = Asm.symbol_end(); it != ie; ++it) {
    const MCSymbol &Symbol = it->getSymbol();

    // Ignore non-linker visible symbols.
    if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
      continue;

    if (!it->isExternal() && !Symbol.isUndefined())
      continue;

    uint64_t &Entry = StringIndexMap[Symbol.getName()];
    if (!Entry) {
      Entry = StringTable.size();
      StringTable += Symbol.getName();
      StringTable += '\x00';
    }

    MachSymbolData MSD;
    MSD.SymbolData = it;
    MSD.StringIndex = Entry;

    if (Symbol.isUndefined()) {
      MSD.SectionIndex = 0;
      UndefinedSymbolData.push_back(MSD);
    } else if (Symbol.isAbsolute()) {
      MSD.SectionIndex = 0;
      ExternalSymbolData.push_back(MSD);
    } else {
      MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
      assert(MSD.SectionIndex && "Invalid section index!");
      ExternalSymbolData.push_back(MSD);
    }
  }

  // Now add the data for local symbols.
  for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
         ie = Asm.symbol_end(); it != ie; ++it) {
    const MCSymbol &Symbol = it->getSymbol();

    // Ignore non-linker visible symbols.
    if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
      continue;

    if (it->isExternal() || Symbol.isUndefined())
      continue;

    uint64_t &Entry = StringIndexMap[Symbol.getName()];
    if (!Entry) {
      Entry = StringTable.size();
      StringTable += Symbol.getName();
      StringTable += '\x00';
    }

    MachSymbolData MSD;
    MSD.SymbolData = it;
    MSD.StringIndex = Entry;

    if (Symbol.isAbsolute()) {
      MSD.SectionIndex = 0;
      LocalSymbolData.push_back(MSD);
    } else {
      MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
      assert(MSD.SectionIndex && "Invalid section index!");
      LocalSymbolData.push_back(MSD);
    }
  }

  // External and undefined symbols are required to be in lexicographic order.
  std::sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
  std::sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
//.........这里部分代码省略.........

void MCELFStreamer::EmitInstToData(const MCInst &Inst,
                                   const MCSubtargetInfo &STI) {
  MCAssembler &Assembler = getAssembler();
  SmallVector<MCFixup, 4> Fixups;
  SmallString<256> Code;
  raw_svector_ostream VecOS(Code);
  Assembler.getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
  VecOS.flush();

  for (unsigned i = 0, e = Fixups.size(); i != e; ++i)
    fixSymbolsInTLSFixups(Fixups[i].getValue());

  // There are several possibilities here:
  //
  // If bundling is disabled, append the encoded instruction to the current data
  // fragment (or create a new such fragment if the current fragment is not a
  // data fragment).
  //
  // If bundling is enabled:
  // - If we're not in a bundle-locked group, emit the instruction into a
  //   fragment of its own. If there are no fixups registered for the
  //   instruction, emit a MCCompactEncodedInstFragment. Otherwise, emit a
  //   MCDataFragment.
  // - If we're in a bundle-locked group, append the instruction to the current
  //   data fragment because we want all the instructions in a group to get into
  //   the same fragment. Be careful not to do that for the first instruction in
  //   the group, though.
  MCDataFragment *DF;

  if (Assembler.isBundlingEnabled()) {
    MCSection &Sec = *getCurrentSectionOnly();
    if (Assembler.getRelaxAll() && isBundleLocked())
      // If the -mc-relax-all flag is used and we are bundle-locked, we re-use
      // the current bundle group.
      DF = BundleGroups.back();
    else if (Assembler.getRelaxAll() && !isBundleLocked())
      // When not in a bundle-locked group and the -mc-relax-all flag is used,
      // we create a new temporary fragment which will be later merged into
      // the current fragment.
      DF = new MCDataFragment();
    else if (isBundleLocked() && !Sec.isBundleGroupBeforeFirstInst())
      // If we are bundle-locked, we re-use the current fragment.
      // The bundle-locking directive ensures this is a new data fragment.
      DF = cast<MCDataFragment>(getCurrentFragment());
    else if (!isBundleLocked() && Fixups.size() == 0) {
      // Optimize memory usage by emitting the instruction to a
      // MCCompactEncodedInstFragment when not in a bundle-locked group and
      // there are no fixups registered.
      MCCompactEncodedInstFragment *CEIF = new MCCompactEncodedInstFragment();
      insert(CEIF);
      CEIF->getContents().append(Code.begin(), Code.end());
      return;
    } else {
      DF = new MCDataFragment();
      insert(DF);
    }
    if (Sec.getBundleLockState() == MCSection::BundleLockedAlignToEnd) {
      // If this fragment is for a group marked "align_to_end", set a flag
      // in the fragment. This can happen after the fragment has already been
      // created if there are nested bundle_align groups and an inner one
      // is the one marked align_to_end.
      DF->setAlignToBundleEnd(true);
    }

    // We're now emitting an instruction in a bundle group, so this flag has
    // to be turned off.
    Sec.setBundleGroupBeforeFirstInst(false);
  } else {
    DF = getOrCreateDataFragment();
  }

  // Add the fixups and data.
  for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
    Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
    DF->getFixups().push_back(Fixups[i]);
  }
  DF->setHasInstructions(true);
  DF->getContents().append(Code.begin(), Code.end());

  if (Assembler.isBundlingEnabled() && Assembler.getRelaxAll()) {
    if (!isBundleLocked()) {
      mergeFragment(getOrCreateDataFragment(), DF);
      delete DF;
    }
  }
}