Import prebuilt clang toolchain for linux.
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+//===- MCAssembler.h - Object File Generation -------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCASSEMBLER_H
+#define LLVM_MC_MCASSEMBLER_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/BinaryFormat/MachO.h"
+#include "llvm/MC/MCDirectives.h"
+#include "llvm/MC/MCDwarf.h"
+#include "llvm/MC/MCFixup.h"
+#include "llvm/MC/MCFragment.h"
+#include "llvm/MC/MCLinkerOptimizationHint.h"
+#include "llvm/MC/MCSymbol.h"
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace llvm {
+
+class MCAsmBackend;
+class MCAsmLayout;
+class MCContext;
+class MCCodeEmitter;
+class MCFragment;
+class MCObjectWriter;
+class MCSection;
+class MCValue;
+
+// FIXME: This really doesn't belong here. See comments below.
+struct IndirectSymbolData {
+  MCSymbol *Symbol;
+  MCSection *Section;
+};
+
+// FIXME: Ditto this. Purely so the Streamer and the ObjectWriter can talk
+// to one another.
+struct DataRegionData {
+  // This enum should be kept in sync w/ the mach-o definition in
+  // llvm/Object/MachOFormat.h.
+  enum KindTy { Data = 1, JumpTable8, JumpTable16, JumpTable32 } Kind;
+  MCSymbol *Start;
+  MCSymbol *End;
+};
+
+class MCAssembler {
+  friend class MCAsmLayout;
+
+public:
+  using SectionListType = std::vector<MCSection *>;
+  using SymbolDataListType = std::vector<const MCSymbol *>;
+
+  using const_iterator = pointee_iterator<SectionListType::const_iterator>;
+  using iterator = pointee_iterator<SectionListType::iterator>;
+
+  using const_symbol_iterator =
+      pointee_iterator<SymbolDataListType::const_iterator>;
+  using symbol_iterator = pointee_iterator<SymbolDataListType::iterator>;
+
+  using symbol_range = iterator_range<symbol_iterator>;
+  using const_symbol_range = iterator_range<const_symbol_iterator>;
+
+  using const_indirect_symbol_iterator =
+      std::vector<IndirectSymbolData>::const_iterator;
+  using indirect_symbol_iterator = std::vector<IndirectSymbolData>::iterator;
+
+  using const_data_region_iterator =
+      std::vector<DataRegionData>::const_iterator;
+  using data_region_iterator = std::vector<DataRegionData>::iterator;
+
+  /// MachO specific deployment target version info.
+  // A Major version of 0 indicates that no version information was supplied
+  // and so the corresponding load command should not be emitted.
+  using VersionInfoType = struct {
+    bool EmitBuildVersion;
+    union {
+      MCVersionMinType Type;          ///< Used when EmitBuildVersion==false.
+      MachO::PlatformType Platform;   ///< Used when EmitBuildVersion==true.
+    } TypeOrPlatform;
+    unsigned Major;
+    unsigned Minor;
+    unsigned Update;
+  };
+
+private:
+  MCContext &Context;
+
+  MCAsmBackend &Backend;
+
+  MCCodeEmitter &Emitter;
+
+  MCObjectWriter &Writer;
+
+  SectionListType Sections;
+
+  SymbolDataListType Symbols;
+
+  std::vector<IndirectSymbolData> IndirectSymbols;
+
+  std::vector<DataRegionData> DataRegions;
+
+  /// The list of linker options to propagate into the object file.
+  std::vector<std::vector<std::string>> LinkerOptions;
+
+  /// List of declared file names
+  std::vector<std::string> FileNames;
+
+  MCDwarfLineTableParams LTParams;
+
+  /// The set of function symbols for which a .thumb_func directive has
+  /// been seen.
+  //
+  // FIXME: We really would like this in target specific code rather than
+  // here. Maybe when the relocation stuff moves to target specific,
+  // this can go with it? The streamer would need some target specific
+  // refactoring too.
+  mutable SmallPtrSet<const MCSymbol *, 32> ThumbFuncs;
+
+  /// \brief The bundle alignment size currently set in the assembler.
+  ///
+  /// By default it's 0, which means bundling is disabled.
+  unsigned BundleAlignSize;
+
+  bool RelaxAll : 1;
+  bool SubsectionsViaSymbols : 1;
+  bool IncrementalLinkerCompatible : 1;
+
+  /// ELF specific e_header flags
+  // It would be good if there were an MCELFAssembler class to hold this.
+  // ELF header flags are used both by the integrated and standalone assemblers.
+  // Access to the flags is necessary in cases where assembler directives affect
+  // which flags to be set.
+  unsigned ELFHeaderEFlags;
+
+  /// Used to communicate Linker Optimization Hint information between
+  /// the Streamer and the .o writer
+  MCLOHContainer LOHContainer;
+
+  VersionInfoType VersionInfo;
+
+  /// Evaluate a fixup to a relocatable expression and the value which should be
+  /// placed into the fixup.
+  ///
+  /// \param Layout The layout to use for evaluation.
+  /// \param Fixup The fixup to evaluate.
+  /// \param DF The fragment the fixup is inside.
+  /// \param Target [out] On return, the relocatable expression the fixup
+  /// evaluates to.
+  /// \param Value [out] On return, the value of the fixup as currently laid
+  /// out.
+  /// \return Whether the fixup value was fully resolved. This is true if the
+  /// \p Value result is fixed, otherwise the value may change due to
+  /// relocation.
+  bool evaluateFixup(const MCAsmLayout &Layout, const MCFixup &Fixup,
+                     const MCFragment *DF, MCValue &Target,
+                     uint64_t &Value) const;
+
+  /// Check whether a fixup can be satisfied, or whether it needs to be relaxed
+  /// (increased in size, in order to hold its value correctly).
+  bool fixupNeedsRelaxation(const MCFixup &Fixup, const MCRelaxableFragment *DF,
+                            const MCAsmLayout &Layout) const;
+
+  /// Check whether the given fragment needs relaxation.
+  bool fragmentNeedsRelaxation(const MCRelaxableFragment *IF,
+                               const MCAsmLayout &Layout) const;
+
+  /// \brief Perform one layout iteration and return true if any offsets
+  /// were adjusted.
+  bool layoutOnce(MCAsmLayout &Layout);
+
+  /// \brief Perform one layout iteration of the given section and return true
+  /// if any offsets were adjusted.
+  bool layoutSectionOnce(MCAsmLayout &Layout, MCSection &Sec);
+
+  bool relaxInstruction(MCAsmLayout &Layout, MCRelaxableFragment &IF);
+
+  bool relaxPaddingFragment(MCAsmLayout &Layout, MCPaddingFragment &PF);
+
+  bool relaxLEB(MCAsmLayout &Layout, MCLEBFragment &IF);
+
+  bool relaxDwarfLineAddr(MCAsmLayout &Layout, MCDwarfLineAddrFragment &DF);
+  bool relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
+                                   MCDwarfCallFrameFragment &DF);
+  bool relaxCVInlineLineTable(MCAsmLayout &Layout,
+                              MCCVInlineLineTableFragment &DF);
+  bool relaxCVDefRange(MCAsmLayout &Layout, MCCVDefRangeFragment &DF);
+
+  /// finishLayout - Finalize a layout, including fragment lowering.
+  void finishLayout(MCAsmLayout &Layout);
+
+  std::tuple<MCValue, uint64_t, bool>
+  handleFixup(const MCAsmLayout &Layout, MCFragment &F, const MCFixup &Fixup);
+
+public:
+  std::vector<std::pair<StringRef, const MCSymbol *>> Symvers;
+
+  /// Construct a new assembler instance.
+  //
+  // FIXME: How are we going to parameterize this? Two obvious options are stay
+  // concrete and require clients to pass in a target like object. The other
+  // option is to make this abstract, and have targets provide concrete
+  // implementations as we do with AsmParser.
+  MCAssembler(MCContext &Context, MCAsmBackend &Backend,
+              MCCodeEmitter &Emitter, MCObjectWriter &Writer);
+  MCAssembler(const MCAssembler &) = delete;
+  MCAssembler &operator=(const MCAssembler &) = delete;
+  ~MCAssembler();
+
+  /// Compute the effective fragment size assuming it is laid out at the given
+  /// \p SectionAddress and \p FragmentOffset.
+  uint64_t computeFragmentSize(const MCAsmLayout &Layout,
+                               const MCFragment &F) const;
+
+  /// Find the symbol which defines the atom containing the given symbol, or
+  /// null if there is no such symbol.
+  const MCSymbol *getAtom(const MCSymbol &S) const;
+
+  /// Check whether a particular symbol is visible to the linker and is required
+  /// in the symbol table, or whether it can be discarded by the assembler. This
+  /// also effects whether the assembler treats the label as potentially
+  /// defining a separate atom.
+  bool isSymbolLinkerVisible(const MCSymbol &SD) const;
+
+  /// Emit the section contents using the given object writer.
+  void writeSectionData(const MCSection *Section,
+                        const MCAsmLayout &Layout) const;
+
+  /// Check whether a given symbol has been flagged with .thumb_func.
+  bool isThumbFunc(const MCSymbol *Func) const;
+
+  /// Flag a function symbol as the target of a .thumb_func directive.
+  void setIsThumbFunc(const MCSymbol *Func) { ThumbFuncs.insert(Func); }
+
+  /// ELF e_header flags
+  unsigned getELFHeaderEFlags() const { return ELFHeaderEFlags; }
+  void setELFHeaderEFlags(unsigned Flags) { ELFHeaderEFlags = Flags; }
+
+  /// MachO deployment target version information.
+  const VersionInfoType &getVersionInfo() const { return VersionInfo; }
+  void setVersionMin(MCVersionMinType Type, unsigned Major, unsigned Minor,
+                     unsigned Update) {
+    VersionInfo.EmitBuildVersion = false;
+    VersionInfo.TypeOrPlatform.Type = Type;
+    VersionInfo.Major = Major;
+    VersionInfo.Minor = Minor;
+    VersionInfo.Update = Update;
+  }
+  void setBuildVersion(MachO::PlatformType Platform, unsigned Major,
+                       unsigned Minor, unsigned Update) {
+    VersionInfo.EmitBuildVersion = true;
+    VersionInfo.TypeOrPlatform.Platform = Platform;
+    VersionInfo.Major = Major;
+    VersionInfo.Minor = Minor;
+    VersionInfo.Update = Update;
+  }
+
+  /// Reuse an assembler instance
+  ///
+  void reset();
+
+  MCContext &getContext() const { return Context; }
+
+  MCAsmBackend &getBackend() const { return Backend; }
+
+  MCCodeEmitter &getEmitter() const { return Emitter; }
+
+  MCObjectWriter &getWriter() const { return Writer; }
+
+  MCDwarfLineTableParams getDWARFLinetableParams() const { return LTParams; }
+  void setDWARFLinetableParams(MCDwarfLineTableParams P) { LTParams = P; }
+
+  /// Finish - Do final processing and write the object to the output stream.
+  /// \p Writer is used for custom object writer (as the MCJIT does),
+  /// if not specified it is automatically created from backend.
+  void Finish();
+
+  // Layout all section and prepare them for emission.
+  void layout(MCAsmLayout &Layout);
+
+  // FIXME: This does not belong here.
+  bool getSubsectionsViaSymbols() const { return SubsectionsViaSymbols; }
+  void setSubsectionsViaSymbols(bool Value) { SubsectionsViaSymbols = Value; }
+
+  bool isIncrementalLinkerCompatible() const {
+    return IncrementalLinkerCompatible;
+  }
+  void setIncrementalLinkerCompatible(bool Value) {
+    IncrementalLinkerCompatible = Value;
+  }
+
+  bool getRelaxAll() const { return RelaxAll; }
+  void setRelaxAll(bool Value) { RelaxAll = Value; }
+
+  bool isBundlingEnabled() const { return BundleAlignSize != 0; }
+
+  unsigned getBundleAlignSize() const { return BundleAlignSize; }
+
+  void setBundleAlignSize(unsigned Size) {
+    assert((Size == 0 || !(Size & (Size - 1))) &&
+           "Expect a power-of-two bundle align size");
+    BundleAlignSize = Size;
+  }
+
+  /// \name Section List Access
+  /// @{
+
+  iterator begin() { return Sections.begin(); }
+  const_iterator begin() const { return Sections.begin(); }
+
+  iterator end() { return Sections.end(); }
+  const_iterator end() const { return Sections.end(); }
+
+  size_t size() const { return Sections.size(); }
+
+  /// @}
+  /// \name Symbol List Access
+  /// @{
+  symbol_iterator symbol_begin() { return Symbols.begin(); }
+  const_symbol_iterator symbol_begin() const { return Symbols.begin(); }
+
+  symbol_iterator symbol_end() { return Symbols.end(); }
+  const_symbol_iterator symbol_end() const { return Symbols.end(); }
+
+  symbol_range symbols() { return make_range(symbol_begin(), symbol_end()); }
+  const_symbol_range symbols() const {
+    return make_range(symbol_begin(), symbol_end());
+  }
+
+  size_t symbol_size() const { return Symbols.size(); }
+
+  /// @}
+  /// \name Indirect Symbol List Access
+  /// @{
+
+  // FIXME: This is a total hack, this should not be here. Once things are
+  // factored so that the streamer has direct access to the .o writer, it can
+  // disappear.
+  std::vector<IndirectSymbolData> &getIndirectSymbols() {
+    return IndirectSymbols;
+  }
+
+  indirect_symbol_iterator indirect_symbol_begin() {
+    return IndirectSymbols.begin();
+  }
+  const_indirect_symbol_iterator indirect_symbol_begin() const {
+    return IndirectSymbols.begin();
+  }
+
+  indirect_symbol_iterator indirect_symbol_end() {
+    return IndirectSymbols.end();
+  }
+  const_indirect_symbol_iterator indirect_symbol_end() const {
+    return IndirectSymbols.end();
+  }
+
+  size_t indirect_symbol_size() const { return IndirectSymbols.size(); }
+
+  /// @}
+  /// \name Linker Option List Access
+  /// @{
+
+  std::vector<std::vector<std::string>> &getLinkerOptions() {
+    return LinkerOptions;
+  }
+
+  /// @}
+  /// \name Data Region List Access
+  /// @{
+
+  // FIXME: This is a total hack, this should not be here. Once things are
+  // factored so that the streamer has direct access to the .o writer, it can
+  // disappear.
+  std::vector<DataRegionData> &getDataRegions() { return DataRegions; }
+
+  data_region_iterator data_region_begin() { return DataRegions.begin(); }
+  const_data_region_iterator data_region_begin() const {
+    return DataRegions.begin();
+  }
+
+  data_region_iterator data_region_end() { return DataRegions.end(); }
+  const_data_region_iterator data_region_end() const {
+    return DataRegions.end();
+  }
+
+  size_t data_region_size() const { return DataRegions.size(); }
+
+  /// @}
+  /// \name Data Region List Access
+  /// @{
+
+  // FIXME: This is a total hack, this should not be here. Once things are
+  // factored so that the streamer has direct access to the .o writer, it can
+  // disappear.
+  MCLOHContainer &getLOHContainer() { return LOHContainer; }
+  const MCLOHContainer &getLOHContainer() const {
+    return const_cast<MCAssembler *>(this)->getLOHContainer();
+  }
+  /// @}
+  /// \name Backend Data Access
+  /// @{
+
+  bool registerSection(MCSection &Section);
+
+  void registerSymbol(const MCSymbol &Symbol, bool *Created = nullptr);
+
+  ArrayRef<std::string> getFileNames() { return FileNames; }
+
+  void addFileName(StringRef FileName) {
+    if (!is_contained(FileNames, FileName))
+      FileNames.push_back(FileName);
+  }
+
+  /// \brief Write the necessary bundle padding to the given object writer.
+  /// Expects a fragment \p F containing instructions and its size \p FSize.
+  void writeFragmentPadding(const MCFragment &F, uint64_t FSize,
+                            MCObjectWriter *OW) const;
+
+  /// @}
+
+  void dump() const;
+};
+
+/// \brief Compute the amount of padding required before the fragment \p F to
+/// obey bundling restrictions, where \p FOffset is the fragment's offset in
+/// its section and \p FSize is the fragment's size.
+uint64_t computeBundlePadding(const MCAssembler &Assembler, const MCFragment *F,
+                              uint64_t FOffset, uint64_t FSize);
+
+} // end namespace llvm
+
+#endif // LLVM_MC_MCASSEMBLER_H