text: //===- lib/MC/MCContext.cpp - Machine Code Context ------------------------===//
  //
  //                     The LLVM37 Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm37/MC/MCContext.h"
  #include "llvm37/ADT/SmallString.h"
  #include "llvm37/ADT/Twine.h"
  #include "llvm37/MC/MCAssembler.h"
  #include "llvm37/MC/MCAsmInfo.h"
  #include "llvm37/MC/MCDwarf.h"
  #include "llvm37/MC/MCLabel.h"
  #include "llvm37/MC/MCObjectFileInfo.h"
  #include "llvm37/MC/MCRegisterInfo.h"
  #include "llvm37/MC/MCSectionCOFF.h"
  #include "llvm37/MC/MCSectionELF.h"
  #include "llvm37/MC/MCSectionMachO.h"
  #include "llvm37/MC/MCStreamer.h"
  #include "llvm37/MC/MCSymbolCOFF.h"
  #include "llvm37/MC/MCSymbolELF.h"
  #include "llvm37/MC/MCSymbolMachO.h"
  #include "llvm37/Support/ELF.h"
  #include "llvm37/Support/ErrorHandling.h"
  #include "llvm37/Support/FileSystem.h"
  #include "llvm37/Support/MemoryBuffer.h"
  #include "llvm37/Support/Signals.h"
  #include "llvm37/Support/SourceMgr.h"
  #include <map>
  
  using namespace llvm37;
  
  MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
                       const MCObjectFileInfo *mofi, const SourceMgr *mgr,
                       bool DoAutoReset)
      : SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi), Allocator(),
        Symbols(Allocator), UsedNames(Allocator),
        CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0), DwarfLocSeen(false),
        GenDwarfForAssembly(false), GenDwarfFileNumber(0), DwarfVersion(4),
        AllowTemporaryLabels(true), DwarfCompileUnitID(0),
        AutoReset(DoAutoReset) {
  
    std::error_code EC = llvm37::sys::fs::current_path(CompilationDir);
    if (EC)
      CompilationDir.clear();
  
    SecureLogFile = getenv("AS_SECURE_LOG_FILE");
    SecureLog = nullptr;
    SecureLogUsed = false;
  
    if (SrcMgr && SrcMgr->getNumBuffers())
      MainFileName =
          SrcMgr->getMemoryBuffer(SrcMgr->getMainFileID())->getBufferIdentifier();
  }
  
  MCContext::~MCContext() {
    if (AutoReset)
      reset();
  
    // NOTE: The symbols are all allocated out of a bump pointer allocator,
    // we don't need to free them here.
  
    // If the stream for the .secure_log_unique directive was created free it.
    delete (raw_ostream *)SecureLog;
  }
  
  //===----------------------------------------------------------------------===//
  // Module Lifetime Management
  //===----------------------------------------------------------------------===//
  
  void MCContext::reset() {
    // Call the destructors so the fragments are freed
    for (auto &I : ELFUniquingMap)
      I.second->~MCSectionELF();
    for (auto &I : COFFUniquingMap)
      I.second->~MCSectionCOFF();
    for (auto &I : MachOUniquingMap)
      I.second->~MCSectionMachO();
  
    UsedNames.clear();
    Symbols.clear();
    Allocator.Reset();
    Instances.clear();
    CompilationDir.clear();
    MainFileName.clear();
    MCDwarfLineTablesCUMap.clear();
    SectionsForRanges.clear();
    MCGenDwarfLabelEntries.clear();
    DwarfDebugFlags = StringRef();
    DwarfCompileUnitID = 0;
    CurrentDwarfLoc = MCDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0);
  
    MachOUniquingMap.clear();
    ELFUniquingMap.clear();
    COFFUniquingMap.clear();
  
    NextID.clear();
    AllowTemporaryLabels = true;
    DwarfLocSeen = false;
    GenDwarfForAssembly = false;
    GenDwarfFileNumber = 0;
  }
  
  //===----------------------------------------------------------------------===//
  // Symbol Manipulation
  //===----------------------------------------------------------------------===//
  
  MCSymbol *MCContext::getOrCreateSymbol(const Twine &Name) {
    SmallString<128> NameSV;
    StringRef NameRef = Name.toStringRef(NameSV);
  
    assert(!NameRef.empty() && "Normal symbols cannot be unnamed!");
  
    MCSymbol *&Sym = Symbols[NameRef];
    if (!Sym)
      Sym = createSymbol(NameRef, false, false);
  
    return Sym;
  }
  
  MCSymbolELF *MCContext::getOrCreateSectionSymbol(const MCSectionELF &Section) {
    MCSymbolELF *&Sym = SectionSymbols[&Section];
    if (Sym)
      return Sym;
  
    StringRef Name = Section.getSectionName();
  
    MCSymbol *&OldSym = Symbols[Name];
    if (OldSym && OldSym->isUndefined()) {
      Sym = cast<MCSymbolELF>(OldSym);
      return Sym;
    }
  
    auto NameIter = UsedNames.insert(std::make_pair(Name, true)).first;
    Sym = new (&*NameIter, *this) MCSymbolELF(&*NameIter, /*isTemporary*/ false);
  
    if (!OldSym)
      OldSym = Sym;
  
    return Sym;
  }
  
  MCSymbol *MCContext::getOrCreateFrameAllocSymbol(StringRef FuncName,
                                                   unsigned Idx) {
    return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName +
                             "$frame_escape_" + Twine(Idx));
  }
  
  MCSymbol *MCContext::getOrCreateParentFrameOffsetSymbol(StringRef FuncName) {
    return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName +
                             "$parent_frame_offset");
  }
  
  MCSymbol *MCContext::getOrCreateLSDASymbol(StringRef FuncName) {
    return getOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + "__ehtable$" +
                             FuncName);
  }
  
  MCSymbol *MCContext::createSymbolImpl(const StringMapEntry<bool> *Name,
                                        bool IsTemporary) {
    if (MOFI) {
      switch (MOFI->getObjectFileType()) {
      case MCObjectFileInfo::IsCOFF:
        return new (Name, *this) MCSymbolCOFF(Name, IsTemporary);
      case MCObjectFileInfo::IsELF:
        return new (Name, *this) MCSymbolELF(Name, IsTemporary);
      case MCObjectFileInfo::IsMachO:
        return new (Name, *this) MCSymbolMachO(Name, IsTemporary);
      }
    }
    return new (Name, *this) MCSymbol(MCSymbol::SymbolKindUnset, Name,
                                      IsTemporary);
  }
  
  MCSymbol *MCContext::createSymbol(StringRef Name, bool AlwaysAddSuffix,
                                    bool CanBeUnnamed) {
    if (CanBeUnnamed && !UseNamesOnTempLabels)
      return createSymbolImpl(nullptr, true);
  
    // Determine whether this is an user writter assembler temporary or normal
    // label, if used.
    bool IsTemporary = CanBeUnnamed;
    if (AllowTemporaryLabels && !IsTemporary)
      IsTemporary = Name.startswith(MAI->getPrivateGlobalPrefix());
  
    SmallString<128> NewName = Name;
    bool AddSuffix = AlwaysAddSuffix;
    unsigned &NextUniqueID = NextID[Name];
    for (;;) {
      if (AddSuffix) {
        NewName.resize(Name.size());
        raw_svector_ostream(NewName) << NextUniqueID++;
      }
      auto NameEntry = UsedNames.insert(std::make_pair(NewName, true));
      if (NameEntry.second) {
        // Ok, we found a name. Have the MCSymbol object itself refer to the copy
        // of the string that is embedded in the UsedNames entry.
        return createSymbolImpl(&*NameEntry.first, IsTemporary);
      }
      assert(IsTemporary && "Cannot rename non-temporary symbols");
      AddSuffix = true;
    }
    llvm37_unreachable("Infinite loop");
  }
  
  MCSymbol *MCContext::createTempSymbol(const Twine &Name, bool AlwaysAddSuffix,
                                        bool CanBeUnnamed) {
    SmallString<128> NameSV;
    raw_svector_ostream(NameSV) << MAI->getPrivateGlobalPrefix() << Name;
    return createSymbol(NameSV, AlwaysAddSuffix, CanBeUnnamed);
  }
  
  MCSymbol *MCContext::createLinkerPrivateTempSymbol() {
    SmallString<128> NameSV;
    raw_svector_ostream(NameSV) << MAI->getLinkerPrivateGlobalPrefix() << "tmp";
    return createSymbol(NameSV, true, false);
  }
  
  MCSymbol *MCContext::createTempSymbol(bool CanBeUnnamed) {
    return createTempSymbol("tmp", true, CanBeUnnamed);
  }
  
  unsigned MCContext::NextInstance(unsigned LocalLabelVal) {
    MCLabel *&Label = Instances[LocalLabelVal];
    if (!Label)
      Label = new (*this) MCLabel(0);
    return Label->incInstance();
  }
  
  unsigned MCContext::GetInstance(unsigned LocalLabelVal) {
    MCLabel *&Label = Instances[LocalLabelVal];
    if (!Label)
      Label = new (*this) MCLabel(0);
    return Label->getInstance();
  }
  
  MCSymbol *MCContext::getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal,
                                                         unsigned Instance) {
    MCSymbol *&Sym = LocalSymbols[std::make_pair(LocalLabelVal, Instance)];
    if (!Sym)
      Sym = createTempSymbol(false);
    return Sym;
  }
  
  MCSymbol *MCContext::createDirectionalLocalSymbol(unsigned LocalLabelVal) {
    unsigned Instance = NextInstance(LocalLabelVal);
    return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
  }
  
  MCSymbol *MCContext::getDirectionalLocalSymbol(unsigned LocalLabelVal,
                                                 bool Before) {
    unsigned Instance = GetInstance(LocalLabelVal);
    if (!Before)
      ++Instance;
    return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance);
  }
  
  MCSymbol *MCContext::lookupSymbol(const Twine &Name) const {
    SmallString<128> NameSV;
    StringRef NameRef = Name.toStringRef(NameSV);
    return Symbols.lookup(NameRef);
  }
  
  //===----------------------------------------------------------------------===//
  // Section Management
  //===----------------------------------------------------------------------===//
  
  MCSectionMachO *MCContext::getMachOSection(StringRef Segment, StringRef Section,
                                             unsigned TypeAndAttributes,
                                             unsigned Reserved2, SectionKind Kind,
                                             const char *BeginSymName) {
  
    // We unique sections by their segment/section pair.  The returned section
    // may not have the same flags as the requested section, if so this should be
    // diagnosed by the client as an error.
  
    // Form the name to look up.
    SmallString<64> Name;
    Name += Segment;
    Name.push_back(',');
    Name += Section;
  
    // Do the lookup, if we have a hit, return it.
    MCSectionMachO *&Entry = MachOUniquingMap[Name];
    if (Entry)
      return Entry;
  
    MCSymbol *Begin = nullptr;
    if (BeginSymName)
      Begin = createTempSymbol(BeginSymName, false);
  
    // Otherwise, return a new section.
    return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
                                              Reserved2, Kind, Begin);
  }
  
  void MCContext::renameELFSection(MCSectionELF *Section, StringRef Name) {
    StringRef GroupName;
    if (const MCSymbol *Group = Section->getGroup())
      GroupName = Group->getName();
  
    unsigned UniqueID = Section->getUniqueID();
    ELFUniquingMap.erase(
        ELFSectionKey{Section->getSectionName(), GroupName, UniqueID});
    auto I = ELFUniquingMap.insert(std::make_pair(
                                       ELFSectionKey{Name, GroupName, UniqueID},
                                       Section))
                 .first;
    StringRef CachedName = I->first.SectionName;
    const_cast<MCSectionELF *>(Section)->setSectionName(CachedName);
  }
  
  MCSectionELF *MCContext::createELFRelSection(StringRef Name, unsigned Type,
                                               unsigned Flags, unsigned EntrySize,
                                               const MCSymbolELF *Group,
                                               const MCSectionELF *Associated) {
    StringMap<bool>::iterator I;
    bool Inserted;
    std::tie(I, Inserted) = ELFRelSecNames.insert(std::make_pair(Name, true));
  
    return new (*this)
        MCSectionELF(I->getKey(), Type, Flags, SectionKind::getReadOnly(),
                     EntrySize, Group, true, nullptr, Associated);
  }
  
  MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
                                         unsigned Flags, unsigned EntrySize,
                                         StringRef Group, unsigned UniqueID,
                                         const char *BeginSymName) {
    MCSymbolELF *GroupSym = nullptr;
    if (!Group.empty())
      GroupSym = cast<MCSymbolELF>(getOrCreateSymbol(Group));
  
    return getELFSection(Section, Type, Flags, EntrySize, GroupSym, UniqueID,
                         BeginSymName, nullptr);
  }
  
  MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type,
                                         unsigned Flags, unsigned EntrySize,
                                         const MCSymbolELF *GroupSym,
                                         unsigned UniqueID,
                                         const char *BeginSymName,
                                         const MCSectionELF *Associated) {
    StringRef Group = "";
    if (GroupSym)
      Group = GroupSym->getName();
    // Do the lookup, if we have a hit, return it.
    auto IterBool = ELFUniquingMap.insert(
        std::make_pair(ELFSectionKey{Section, Group, UniqueID}, nullptr));
    auto &Entry = *IterBool.first;
    if (!IterBool.second)
      return Entry.second;
  
    StringRef CachedName = Entry.first.SectionName;
  
    SectionKind Kind;
    if (Flags & ELF::SHF_EXECINSTR)
      Kind = SectionKind::getText();
    else
      Kind = SectionKind::getReadOnly();
  
    MCSymbol *Begin = nullptr;
    if (BeginSymName)
      Begin = createTempSymbol(BeginSymName, false);
  
    MCSectionELF *Result =
        new (*this) MCSectionELF(CachedName, Type, Flags, Kind, EntrySize,
                                 GroupSym, UniqueID, Begin, Associated);
    Entry.second = Result;
    return Result;
  }
  
  MCSectionELF *MCContext::createELFGroupSection(const MCSymbolELF *Group) {
    MCSectionELF *Result = new (*this)
        MCSectionELF(".group", ELF::SHT_GROUP, 0, SectionKind::getReadOnly(), 4,
                     Group, ~0, nullptr, nullptr);
    return Result;
  }
  
  MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
                                           unsigned Characteristics,
                                           SectionKind Kind,
                                           StringRef COMDATSymName, int Selection,
                                           const char *BeginSymName) {
    MCSymbol *COMDATSymbol = nullptr;
    if (!COMDATSymName.empty()) {
      COMDATSymbol = getOrCreateSymbol(COMDATSymName);
      COMDATSymName = COMDATSymbol->getName();
    }
  
    // Do the lookup, if we have a hit, return it.
    COFFSectionKey T{Section, COMDATSymName, Selection};
    auto IterBool = COFFUniquingMap.insert(std::make_pair(T, nullptr));
    auto Iter = IterBool.first;
    if (!IterBool.second)
      return Iter->second;
  
    MCSymbol *Begin = nullptr;
    if (BeginSymName)
      Begin = createTempSymbol(BeginSymName, false);
  
    StringRef CachedName = Iter->first.SectionName;
    MCSectionCOFF *Result = new (*this) MCSectionCOFF(
        CachedName, Characteristics, COMDATSymbol, Selection, Kind, Begin);
  
    Iter->second = Result;
    return Result;
  }
  
  MCSectionCOFF *MCContext::getCOFFSection(StringRef Section,
                                           unsigned Characteristics,
                                           SectionKind Kind,
                                           const char *BeginSymName) {
    return getCOFFSection(Section, Characteristics, Kind, "", 0, BeginSymName);
  }
  
  MCSectionCOFF *MCContext::getCOFFSection(StringRef Section) {
    COFFSectionKey T{Section, "", 0};
    auto Iter = COFFUniquingMap.find(T);
    if (Iter == COFFUniquingMap.end())
      return nullptr;
    return Iter->second;
  }
  
  MCSectionCOFF *MCContext::getAssociativeCOFFSection(MCSectionCOFF *Sec,
                                                      const MCSymbol *KeySym) {
    // Return the normal section if we don't have to be associative.
    if (!KeySym)
      return Sec;
  
    // Make an associative section with the same name and kind as the normal
    // section.
    unsigned Characteristics =
        Sec->getCharacteristics() | COFF::IMAGE_SCN_LNK_COMDAT;
    return getCOFFSection(Sec->getSectionName(), Characteristics, Sec->getKind(),
                          KeySym->getName(),
                          COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE);
  }
  
  //===----------------------------------------------------------------------===//
  // Dwarf Management
  //===----------------------------------------------------------------------===//
  
  /// getDwarfFile - takes a file name an number to place in the dwarf file and
  /// directory tables.  If the file number has already been allocated it is an
  /// error and zero is returned and the client reports the error, else the
  /// allocated file number is returned.  The file numbers may be in any order.
  unsigned MCContext::getDwarfFile(StringRef Directory, StringRef FileName,
                                   unsigned FileNumber, unsigned CUID) {
    MCDwarfLineTable &Table = MCDwarfLineTablesCUMap[CUID];
    return Table.getFile(Directory, FileName, FileNumber);
  }
  
  /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
  /// currently is assigned and false otherwise.
  bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
    const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles = getMCDwarfFiles(CUID);
    if (FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
      return false;
  
    return !MCDwarfFiles[FileNumber].Name.empty();
  }
  
  /// Remove empty sections from SectionStartEndSyms, to avoid generating
  /// useless debug info for them.
  void MCContext::finalizeDwarfSections(MCStreamer &MCOS) {
    SectionsForRanges.remove_if(
        [&](MCSection *Sec) { return !MCOS.mayHaveInstructions(*Sec); });
  }
  
  void MCContext::reportFatalError(SMLoc Loc, const Twine &Msg) const {
  #if 0 // HLSL Change - analysis shows this isn't called on corruption but on paths with no recovery; unwind instead of terminating
    // If we have a source manager and a location, use it. Otherwise just
    // use the generic report_fatal_error().
    if (!SrcMgr || Loc == SMLoc())
      report_fatal_error(Msg, false);
  
    // Use the source manager to print the message.
    SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
  
    // If we reached here, we are failing ungracefully. Run the interrupt handlers
    // to make sure any special cleanups get done, in particular that we remove
    // files registered with RemoveFileOnSignal.
    sys::RunInterruptHandlers();
    exit(1);
  #else
    throw std::exception();
  #endif
  }
  