LCOV - code coverage report
Current view: top level - include/llvm/MC - MCMachObjectWriter.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 14 15 93.3 %
Date: 2018-07-13 00:08:38 Functions: 6 8 75.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- llvm/MC/MCMachObjectWriter.h - Mach Object Writer --------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : 
      10             : #ifndef LLVM_MC_MCMACHOBJECTWRITER_H
      11             : #define LLVM_MC_MCMACHOBJECTWRITER_H
      12             : 
      13             : #include "llvm/ADT/DenseMap.h"
      14             : #include "llvm/ADT/StringRef.h"
      15             : #include "llvm/BinaryFormat/MachO.h"
      16             : #include "llvm/MC/MCExpr.h"
      17             : #include "llvm/MC/MCObjectWriter.h"
      18             : #include "llvm/MC/MCSection.h"
      19             : #include "llvm/MC/StringTableBuilder.h"
      20             : #include <cstdint>
      21             : #include <memory>
      22             : #include <string>
      23             : #include <vector>
      24             : 
      25             : namespace llvm {
      26             : 
      27             : class MachObjectWriter;
      28             : 
      29        3157 : class MCMachObjectTargetWriter : public MCObjectTargetWriter {
      30             :   const unsigned Is64Bit : 1;
      31             :   const uint32_t CPUType;
      32             :   const uint32_t CPUSubtype;
      33             :   unsigned LocalDifference_RIT;
      34             : 
      35             : protected:
      36             :   MCMachObjectTargetWriter(bool Is64Bit_, uint32_t CPUType_,
      37             :                            uint32_t CPUSubtype_);
      38             : 
      39             :   void setLocalDifferenceRelocationType(unsigned Type) {
      40             :     LocalDifference_RIT = Type;
      41             :   }
      42             : 
      43             : public:
      44             :   virtual ~MCMachObjectTargetWriter();
      45             : 
      46        3175 :   virtual Triple::ObjectFormatType getFormat() const { return Triple::MachO; }
      47             :   static bool classof(const MCObjectTargetWriter *W) {
      48             :     return W->getFormat() == Triple::MachO;
      49             :   }
      50             : 
      51             :   /// \name Lifetime Management
      52             :   /// @{
      53             : 
      54           0 :   virtual void reset() {}
      55             : 
      56             :   /// @}
      57             : 
      58             :   /// \name Accessors
      59             :   /// @{
      60             : 
      61       16771 :   bool is64Bit() const { return Is64Bit; }
      62             :   uint32_t getCPUType() const { return CPUType; }
      63             :   uint32_t getCPUSubtype() const { return CPUSubtype; }
      64             :   unsigned getLocalDifferenceRelocationType() const {
      65             :     return LocalDifference_RIT;
      66             :   }
      67             : 
      68             :   /// @}
      69             : 
      70             :   /// \name API
      71             :   /// @{
      72             : 
      73             :   virtual void recordRelocation(MachObjectWriter *Writer, MCAssembler &Asm,
      74             :                                 const MCAsmLayout &Layout,
      75             :                                 const MCFragment *Fragment,
      76             :                                 const MCFixup &Fixup, MCValue Target,
      77             :                                 uint64_t &FixedValue) = 0;
      78             : 
      79             :   /// @}
      80             : };
      81             : 
      82       15785 : class MachObjectWriter : public MCObjectWriter {
      83             :   /// Helper struct for containing some precomputed information on symbols.
      84             :   struct MachSymbolData {
      85             :     const MCSymbol *Symbol;
      86             :     uint64_t StringIndex;
      87             :     uint8_t SectionIndex;
      88             : 
      89             :     // Support lexicographic sorting.
      90             :     bool operator<(const MachSymbolData &RHS) const;
      91             :   };
      92             : 
      93             :   /// The target specific Mach-O writer instance.
      94             :   std::unique_ptr<MCMachObjectTargetWriter> TargetObjectWriter;
      95             : 
      96             :   /// \name Relocation Data
      97             :   /// @{
      98             : 
      99             :   struct RelAndSymbol {
     100             :     const MCSymbol *Sym;
     101             :     MachO::any_relocation_info MRE;
     102             :     RelAndSymbol(const MCSymbol *Sym, const MachO::any_relocation_info &MRE)
     103        3276 :         : Sym(Sym), MRE(MRE) {}
     104             :   };
     105             : 
     106             :   DenseMap<const MCSection *, std::vector<RelAndSymbol>> Relocations;
     107             :   DenseMap<const MCSection *, unsigned> IndirectSymBase;
     108             : 
     109             :   SectionAddrMap SectionAddress;
     110             : 
     111             :   /// @}
     112             :   /// \name Symbol Table Data
     113             :   /// @{
     114             : 
     115             :   StringTableBuilder StringTable{StringTableBuilder::MachO};
     116             :   std::vector<MachSymbolData> LocalSymbolData;
     117             :   std::vector<MachSymbolData> ExternalSymbolData;
     118             :   std::vector<MachSymbolData> UndefinedSymbolData;
     119             : 
     120             :   /// @}
     121             : 
     122             :   MachSymbolData *findSymbolData(const MCSymbol &Sym);
     123             : 
     124             :   void writeWithPadding(StringRef Str, uint64_t Size);
     125             : 
     126             : public:
     127        3175 :   MachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
     128             :                    raw_pwrite_stream &OS, bool IsLittleEndian)
     129        3175 :       : TargetObjectWriter(std::move(MOTW)),
     130       22225 :         W(OS, IsLittleEndian ? support::little : support::big) {}
     131             : 
     132             :   support::endian::Writer W;
     133             : 
     134             :   const MCSymbol &findAliasedSymbol(const MCSymbol &Sym) const;
     135             : 
     136             :   /// \name Lifetime management Methods
     137             :   /// @{
     138             : 
     139             :   void reset() override;
     140             : 
     141             :   /// @}
     142             : 
     143             :   /// \name Utility Methods
     144             :   /// @{
     145             : 
     146             :   bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
     147             : 
     148         315 :   SectionAddrMap &getSectionAddressMap() { return SectionAddress; }
     149             : 
     150             :   uint64_t getSectionAddress(const MCSection *Sec) const {
     151       24218 :     return SectionAddress.lookup(Sec);
     152             :   }
     153             :   uint64_t getSymbolAddress(const MCSymbol &S, const MCAsmLayout &Layout) const;
     154             : 
     155             :   uint64_t getFragmentAddress(const MCFragment *Fragment,
     156             :                               const MCAsmLayout &Layout) const;
     157             : 
     158             :   uint64_t getPaddingSize(const MCSection *SD, const MCAsmLayout &Layout) const;
     159             : 
     160             :   bool doesSymbolRequireExternRelocation(const MCSymbol &S);
     161             : 
     162             :   /// @}
     163             : 
     164             :   /// \name Target Writer Proxy Accessors
     165             :   /// @{
     166             : 
     167             :   bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
     168             :   bool isX86_64() const {
     169        1135 :     uint32_t CPUType = TargetObjectWriter->getCPUType();
     170             :     return CPUType == MachO::CPU_TYPE_X86_64;
     171             :   }
     172             : 
     173             :   /// @}
     174             : 
     175             :   void writeHeader(MachO::HeaderFileType Type, unsigned NumLoadCommands,
     176             :                    unsigned LoadCommandsSize, bool SubsectionsViaSymbols);
     177             : 
     178             :   /// Write a segment load command.
     179             :   ///
     180             :   /// \param NumSections The number of sections in this segment.
     181             :   /// \param SectionDataSize The total size of the sections.
     182             :   void writeSegmentLoadCommand(StringRef Name, unsigned NumSections,
     183             :                                uint64_t VMAddr, uint64_t VMSize,
     184             :                                uint64_t SectionDataStartOffset,
     185             :                                uint64_t SectionDataSize, uint32_t MaxProt,
     186             :                                uint32_t InitProt);
     187             : 
     188             :   void writeSection(const MCAsmLayout &Layout, const MCSection &Sec,
     189             :                     uint64_t VMAddr, uint64_t FileOffset, unsigned Flags,
     190             :                     uint64_t RelocationsStart, unsigned NumRelocations);
     191             : 
     192             :   void writeSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
     193             :                               uint32_t StringTableOffset,
     194             :                               uint32_t StringTableSize);
     195             : 
     196             :   void writeDysymtabLoadCommand(
     197             :       uint32_t FirstLocalSymbol, uint32_t NumLocalSymbols,
     198             :       uint32_t FirstExternalSymbol, uint32_t NumExternalSymbols,
     199             :       uint32_t FirstUndefinedSymbol, uint32_t NumUndefinedSymbols,
     200             :       uint32_t IndirectSymbolOffset, uint32_t NumIndirectSymbols);
     201             : 
     202             :   void writeNlist(MachSymbolData &MSD, const MCAsmLayout &Layout);
     203             : 
     204             :   void writeLinkeditLoadCommand(uint32_t Type, uint32_t DataOffset,
     205             :                                 uint32_t DataSize);
     206             : 
     207             :   void writeLinkerOptionsLoadCommand(const std::vector<std::string> &Options);
     208             : 
     209             :   // FIXME: We really need to improve the relocation validation. Basically, we
     210             :   // want to implement a separate computation which evaluates the relocation
     211             :   // entry as the linker would, and verifies that the resultant fixup value is
     212             :   // exactly what the encoder wanted. This will catch several classes of
     213             :   // problems:
     214             :   //
     215             :   //  - Relocation entry bugs, the two algorithms are unlikely to have the same
     216             :   //    exact bug.
     217             :   //
     218             :   //  - Relaxation issues, where we forget to relax something.
     219             :   //
     220             :   //  - Input errors, where something cannot be correctly encoded. 'as' allows
     221             :   //    these through in many cases.
     222             : 
     223             :   // Add a relocation to be output in the object file. At the time this is
     224             :   // called, the symbol indexes are not know, so if the relocation refers
     225             :   // to a symbol it should be passed as \p RelSymbol so that it can be updated
     226             :   // afterwards. If the relocation doesn't refer to a symbol, nullptr should be
     227             :   // used.
     228        3276 :   void addRelocation(const MCSymbol *RelSymbol, const MCSection *Sec,
     229             :                      MachO::any_relocation_info &MRE) {
     230             :     RelAndSymbol P(RelSymbol, MRE);
     231        6552 :     Relocations[Sec].push_back(P);
     232        3276 :   }
     233             : 
     234             :   void recordScatteredRelocation(const MCAssembler &Asm,
     235             :                                  const MCAsmLayout &Layout,
     236             :                                  const MCFragment *Fragment,
     237             :                                  const MCFixup &Fixup, MCValue Target,
     238             :                                  unsigned Log2Size, uint64_t &FixedValue);
     239             : 
     240             :   void recordTLVPRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
     241             :                             const MCFragment *Fragment, const MCFixup &Fixup,
     242             :                             MCValue Target, uint64_t &FixedValue);
     243             : 
     244             :   void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
     245             :                         const MCFragment *Fragment, const MCFixup &Fixup,
     246             :                         MCValue Target, uint64_t &FixedValue) override;
     247             : 
     248             :   void bindIndirectSymbols(MCAssembler &Asm);
     249             : 
     250             :   /// Compute the symbol table data.
     251             :   void computeSymbolTable(MCAssembler &Asm,
     252             :                           std::vector<MachSymbolData> &LocalSymbolData,
     253             :                           std::vector<MachSymbolData> &ExternalSymbolData,
     254             :                           std::vector<MachSymbolData> &UndefinedSymbolData);
     255             : 
     256             :   void computeSectionAddresses(const MCAssembler &Asm,
     257             :                                const MCAsmLayout &Layout);
     258             : 
     259             :   void executePostLayoutBinding(MCAssembler &Asm,
     260             :                                 const MCAsmLayout &Layout) override;
     261             : 
     262             :   bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
     263             :                                               const MCSymbol &A,
     264             :                                               const MCSymbol &B,
     265             :                                               bool InSet) const override;
     266             : 
     267             :   bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
     268             :                                               const MCSymbol &SymA,
     269             :                                               const MCFragment &FB, bool InSet,
     270             :                                               bool IsPCRel) const override;
     271             : 
     272             :   uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
     273             : };
     274             : 
     275             : /// Construct a new Mach-O writer instance.
     276             : ///
     277             : /// This routine takes ownership of the target writer subclass.
     278             : ///
     279             : /// \param MOTW - The target specific Mach-O writer subclass.
     280             : /// \param OS - The stream to write to.
     281             : /// \returns The constructed object writer.
     282             : std::unique_ptr<MCObjectWriter>
     283             : createMachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
     284             :                        raw_pwrite_stream &OS, bool IsLittleEndian);
     285             : 
     286             : } // end namespace llvm
     287             : 
     288             : #endif // LLVM_MC_MCMACHOBJECTWRITER_H

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