LCOV - code coverage report
Current view: top level - include/llvm/MC - MCMachObjectWriter.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 13 14 92.9 %
Date: 2018-05-20 00:06:23 Functions: 5 7 71.4 %
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        3118 : class MCMachObjectTargetWriter {
      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             :   /// \name Lifetime Management
      47             :   /// @{
      48             : 
      49           0 :   virtual void reset() {}
      50             : 
      51             :   /// @}
      52             : 
      53             :   /// \name Accessors
      54             :   /// @{
      55             : 
      56       16237 :   bool is64Bit() const { return Is64Bit; }
      57             :   uint32_t getCPUType() const { return CPUType; }
      58             :   uint32_t getCPUSubtype() const { return CPUSubtype; }
      59             :   unsigned getLocalDifferenceRelocationType() const {
      60             :     return LocalDifference_RIT;
      61             :   }
      62             : 
      63             :   /// @}
      64             : 
      65             :   /// \name API
      66             :   /// @{
      67             : 
      68             :   virtual void recordRelocation(MachObjectWriter *Writer, MCAssembler &Asm,
      69             :                                 const MCAsmLayout &Layout,
      70             :                                 const MCFragment *Fragment,
      71             :                                 const MCFixup &Fixup, MCValue Target,
      72             :                                 uint64_t &FixedValue) = 0;
      73             : 
      74             :   /// @}
      75             : };
      76             : 
      77       15590 : class MachObjectWriter : public MCObjectWriter {
      78             :   /// Helper struct for containing some precomputed information on symbols.
      79             :   struct MachSymbolData {
      80             :     const MCSymbol *Symbol;
      81             :     uint64_t StringIndex;
      82             :     uint8_t SectionIndex;
      83             : 
      84             :     // Support lexicographic sorting.
      85             :     bool operator<(const MachSymbolData &RHS) const;
      86             :   };
      87             : 
      88             :   /// The target specific Mach-O writer instance.
      89             :   std::unique_ptr<MCMachObjectTargetWriter> TargetObjectWriter;
      90             : 
      91             :   /// \name Relocation Data
      92             :   /// @{
      93             : 
      94             :   struct RelAndSymbol {
      95             :     const MCSymbol *Sym;
      96             :     MachO::any_relocation_info MRE;
      97             :     RelAndSymbol(const MCSymbol *Sym, const MachO::any_relocation_info &MRE)
      98        3174 :         : Sym(Sym), MRE(MRE) {}
      99             :   };
     100             : 
     101             :   DenseMap<const MCSection *, std::vector<RelAndSymbol>> Relocations;
     102             :   DenseMap<const MCSection *, unsigned> IndirectSymBase;
     103             : 
     104             :   SectionAddrMap SectionAddress;
     105             : 
     106             :   /// @}
     107             :   /// \name Symbol Table Data
     108             :   /// @{
     109             : 
     110             :   StringTableBuilder StringTable{StringTableBuilder::MachO};
     111             :   std::vector<MachSymbolData> LocalSymbolData;
     112             :   std::vector<MachSymbolData> ExternalSymbolData;
     113             :   std::vector<MachSymbolData> UndefinedSymbolData;
     114             : 
     115             :   /// @}
     116             : 
     117             :   MachSymbolData *findSymbolData(const MCSymbol &Sym);
     118             : 
     119             : public:
     120        3136 :   MachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
     121             :                    raw_pwrite_stream &OS, bool IsLittleEndian)
     122        3136 :       : MCObjectWriter(OS, IsLittleEndian),
     123       18816 :         TargetObjectWriter(std::move(MOTW)) {}
     124             : 
     125             :   const MCSymbol &findAliasedSymbol(const MCSymbol &Sym) const;
     126             : 
     127             :   /// \name Lifetime management Methods
     128             :   /// @{
     129             : 
     130             :   void reset() override;
     131             : 
     132             :   /// @}
     133             : 
     134             :   /// \name Utility Methods
     135             :   /// @{
     136             : 
     137             :   bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
     138             : 
     139         288 :   SectionAddrMap &getSectionAddressMap() { return SectionAddress; }
     140             : 
     141             :   uint64_t getSectionAddress(const MCSection *Sec) const {
     142       23308 :     return SectionAddress.lookup(Sec);
     143             :   }
     144             :   uint64_t getSymbolAddress(const MCSymbol &S, const MCAsmLayout &Layout) const;
     145             : 
     146             :   uint64_t getFragmentAddress(const MCFragment *Fragment,
     147             :                               const MCAsmLayout &Layout) const;
     148             : 
     149             :   uint64_t getPaddingSize(const MCSection *SD, const MCAsmLayout &Layout) const;
     150             : 
     151             :   bool doesSymbolRequireExternRelocation(const MCSymbol &S);
     152             : 
     153             :   /// @}
     154             : 
     155             :   /// \name Target Writer Proxy Accessors
     156             :   /// @{
     157             : 
     158             :   bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
     159             :   bool isX86_64() const {
     160        1111 :     uint32_t CPUType = TargetObjectWriter->getCPUType();
     161             :     return CPUType == MachO::CPU_TYPE_X86_64;
     162             :   }
     163             : 
     164             :   /// @}
     165             : 
     166             :   void writeHeader(MachO::HeaderFileType Type, unsigned NumLoadCommands,
     167             :                    unsigned LoadCommandsSize, bool SubsectionsViaSymbols);
     168             : 
     169             :   /// Write a segment load command.
     170             :   ///
     171             :   /// \param NumSections The number of sections in this segment.
     172             :   /// \param SectionDataSize The total size of the sections.
     173             :   void writeSegmentLoadCommand(StringRef Name, unsigned NumSections,
     174             :                                uint64_t VMAddr, uint64_t VMSize,
     175             :                                uint64_t SectionDataStartOffset,
     176             :                                uint64_t SectionDataSize, uint32_t MaxProt,
     177             :                                uint32_t InitProt);
     178             : 
     179             :   void writeSection(const MCAsmLayout &Layout, const MCSection &Sec,
     180             :                     uint64_t VMAddr, uint64_t FileOffset, unsigned Flags,
     181             :                     uint64_t RelocationsStart, unsigned NumRelocations);
     182             : 
     183             :   void writeSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
     184             :                               uint32_t StringTableOffset,
     185             :                               uint32_t StringTableSize);
     186             : 
     187             :   void writeDysymtabLoadCommand(
     188             :       uint32_t FirstLocalSymbol, uint32_t NumLocalSymbols,
     189             :       uint32_t FirstExternalSymbol, uint32_t NumExternalSymbols,
     190             :       uint32_t FirstUndefinedSymbol, uint32_t NumUndefinedSymbols,
     191             :       uint32_t IndirectSymbolOffset, uint32_t NumIndirectSymbols);
     192             : 
     193             :   void writeNlist(MachSymbolData &MSD, const MCAsmLayout &Layout);
     194             : 
     195             :   void writeLinkeditLoadCommand(uint32_t Type, uint32_t DataOffset,
     196             :                                 uint32_t DataSize);
     197             : 
     198             :   void writeLinkerOptionsLoadCommand(const std::vector<std::string> &Options);
     199             : 
     200             :   // FIXME: We really need to improve the relocation validation. Basically, we
     201             :   // want to implement a separate computation which evaluates the relocation
     202             :   // entry as the linker would, and verifies that the resultant fixup value is
     203             :   // exactly what the encoder wanted. This will catch several classes of
     204             :   // problems:
     205             :   //
     206             :   //  - Relocation entry bugs, the two algorithms are unlikely to have the same
     207             :   //    exact bug.
     208             :   //
     209             :   //  - Relaxation issues, where we forget to relax something.
     210             :   //
     211             :   //  - Input errors, where something cannot be correctly encoded. 'as' allows
     212             :   //    these through in many cases.
     213             : 
     214             :   // Add a relocation to be output in the object file. At the time this is
     215             :   // called, the symbol indexes are not know, so if the relocation refers
     216             :   // to a symbol it should be passed as \p RelSymbol so that it can be updated
     217             :   // afterwards. If the relocation doesn't refer to a symbol, nullptr should be
     218             :   // used.
     219        3174 :   void addRelocation(const MCSymbol *RelSymbol, const MCSection *Sec,
     220             :                      MachO::any_relocation_info &MRE) {
     221             :     RelAndSymbol P(RelSymbol, MRE);
     222        6348 :     Relocations[Sec].push_back(P);
     223        3174 :   }
     224             : 
     225             :   void recordScatteredRelocation(const MCAssembler &Asm,
     226             :                                  const MCAsmLayout &Layout,
     227             :                                  const MCFragment *Fragment,
     228             :                                  const MCFixup &Fixup, MCValue Target,
     229             :                                  unsigned Log2Size, uint64_t &FixedValue);
     230             : 
     231             :   void recordTLVPRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
     232             :                             const MCFragment *Fragment, const MCFixup &Fixup,
     233             :                             MCValue Target, uint64_t &FixedValue);
     234             : 
     235             :   void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
     236             :                         const MCFragment *Fragment, const MCFixup &Fixup,
     237             :                         MCValue Target, uint64_t &FixedValue) override;
     238             : 
     239             :   void bindIndirectSymbols(MCAssembler &Asm);
     240             : 
     241             :   /// Compute the symbol table data.
     242             :   void computeSymbolTable(MCAssembler &Asm,
     243             :                           std::vector<MachSymbolData> &LocalSymbolData,
     244             :                           std::vector<MachSymbolData> &ExternalSymbolData,
     245             :                           std::vector<MachSymbolData> &UndefinedSymbolData);
     246             : 
     247             :   void computeSectionAddresses(const MCAssembler &Asm,
     248             :                                const MCAsmLayout &Layout);
     249             : 
     250             :   void executePostLayoutBinding(MCAssembler &Asm,
     251             :                                 const MCAsmLayout &Layout) override;
     252             : 
     253             :   bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
     254             :                                               const MCSymbol &A,
     255             :                                               const MCSymbol &B,
     256             :                                               bool InSet) const override;
     257             : 
     258             :   bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
     259             :                                               const MCSymbol &SymA,
     260             :                                               const MCFragment &FB, bool InSet,
     261             :                                               bool IsPCRel) const override;
     262             : 
     263             :   void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
     264             : };
     265             : 
     266             : /// Construct a new Mach-O writer instance.
     267             : ///
     268             : /// This routine takes ownership of the target writer subclass.
     269             : ///
     270             : /// \param MOTW - The target specific Mach-O writer subclass.
     271             : /// \param OS - The stream to write to.
     272             : /// \returns The constructed object writer.
     273             : std::unique_ptr<MCObjectWriter>
     274             : createMachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
     275             :                        raw_pwrite_stream &OS, bool IsLittleEndian);
     276             : 
     277             : } // end namespace llvm
     278             : 
     279             : #endif // LLVM_MC_MCMACHOBJECTWRITER_H

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