Refactor MachO relocation generaration into the Target directories.

Move the target-specific RecordRelocation logic out of the generic MC
MachObjectWriter and into the target-specific object writers. This allows
nuking quite a bit of target knowledge from the supposedly target-independent
bits in lib/MC.

llvm-svn: 133844

Author: Jim Grosbach

llvm/include/llvm/MC/MCMachObjectWriter.h

@@ -10,11 +10,20 @@
 #ifndef LLVM_MC_MCMACHOBJECTWRITER_H
 #define LLVM_MC_MCMACHOBJECTWRITER_H
 
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCObjectWriter.h"
+#include "llvm/Object/MachOFormat.h"
 #include "llvm/Support/DataTypes.h"
+#include <vector>
 
 namespace llvm {
 
+class MCSectionData;
+class MachObjectWriter;
+
 class MCMachObjectTargetWriter {
   const unsigned Is64Bit : 1;
   const uint32_t CPUType;
@@ -48,8 +57,191 @@ class MCMachObjectTargetWriter {
   }
 
   /// @}
+
+  /// @name API
+  /// @{
+
+  virtual void RecordRelocation(MachObjectWriter *Writer,
+                                const MCAssembler &Asm,
+                                const MCAsmLayout &Layout,
+                                const MCFragment *Fragment,
+                                const MCFixup &Fixup,
+                                MCValue Target,
+                                uint64_t &FixedValue) = 0;
+
+  /// @}
 };
 
+class MachObjectWriter : public MCObjectWriter {
+  /// MachSymbolData - Helper struct for containing some precomputed information
+  /// on symbols.
+  struct MachSymbolData {
+    MCSymbolData *SymbolData;
+    uint64_t StringIndex;
+    uint8_t SectionIndex;
+
+    // Support lexicographic sorting.
+    bool operator<(const MachSymbolData &RHS) const;
+  };
+
+  /// The target specific Mach-O writer instance.
+  llvm::OwningPtr<MCMachObjectTargetWriter> TargetObjectWriter;
+
+  /// @name Relocation Data
+  /// @{
+
+  llvm::DenseMap<const MCSectionData*,
+                 std::vector<object::macho::RelocationEntry> > Relocations;
+  llvm::DenseMap<const MCSectionData*, unsigned> IndirectSymBase;
+
+  /// @}
+  /// @name Symbol Table Data
+  /// @{
+
+  SmallString<256> StringTable;
+  std::vector<MachSymbolData> LocalSymbolData;
+  std::vector<MachSymbolData> ExternalSymbolData;
+  std::vector<MachSymbolData> UndefinedSymbolData;
+
+  /// @}
+
+public:
+  MachObjectWriter(MCMachObjectTargetWriter *MOTW, raw_ostream &_OS,
+                   bool _IsLittleEndian)
+    : MCObjectWriter(_OS, _IsLittleEndian), TargetObjectWriter(MOTW) {
+  }
+
+  /// @name Utility Methods
+  /// @{
+
+  bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
+
+  SectionAddrMap SectionAddress;
+
+  SectionAddrMap &getSectionAddressMap() { return SectionAddress; }
+
+  uint64_t getSectionAddress(const MCSectionData* SD) const {
+    return SectionAddress.lookup(SD);
+  }
+  uint64_t getSymbolAddress(const MCSymbolData* SD,
+                            const MCAsmLayout &Layout) const;
+
+  uint64_t getFragmentAddress(const MCFragment *Fragment,
+                              const MCAsmLayout &Layout) const;
+
+  uint64_t getPaddingSize(const MCSectionData *SD,
+                          const MCAsmLayout &Layout) const;
+
+  bool doesSymbolRequireExternRelocation(const MCSymbolData *SD);
+
+  /// @}
+
+  /// @name Target Writer Proxy Accessors
+  /// @{
+
+  bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
+  bool isARM() const {
+    uint32_t CPUType = TargetObjectWriter->getCPUType() &
+      ~object::mach::CTFM_ArchMask;
+    return CPUType == object::mach::CTM_ARM;
+  }
+
+  /// @}
+
+  void WriteHeader(unsigned NumLoadCommands, unsigned LoadCommandsSize,
+                   bool SubsectionsViaSymbols);
+
+  /// WriteSegmentLoadCommand - Write a segment load command.
+  ///
+  /// \arg NumSections - The number of sections in this segment.
+  /// \arg SectionDataSize - The total size of the sections.
+  void WriteSegmentLoadCommand(unsigned NumSections,
+                               uint64_t VMSize,
+                               uint64_t SectionDataStartOffset,
+                               uint64_t SectionDataSize);
+
+  void WriteSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
+                    const MCSectionData &SD, uint64_t FileOffset,
+                    uint64_t RelocationsStart, unsigned NumRelocations);
+
+  void WriteSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
+                              uint32_t StringTableOffset,
+                              uint32_t StringTableSize);
+
+  void WriteDysymtabLoadCommand(uint32_t FirstLocalSymbol,
+                                uint32_t NumLocalSymbols,
+                                uint32_t FirstExternalSymbol,
+                                uint32_t NumExternalSymbols,
+                                uint32_t FirstUndefinedSymbol,
+                                uint32_t NumUndefinedSymbols,
+                                uint32_t IndirectSymbolOffset,
+                                uint32_t NumIndirectSymbols);
+
+  void WriteNlist(MachSymbolData &MSD, const MCAsmLayout &Layout);
+
+  // FIXME: We really need to improve the relocation validation. Basically, we
+  // want to implement a separate computation which evaluates the relocation
+  // entry as the linker would, and verifies that the resultant fixup value is
+  // exactly what the encoder wanted. This will catch several classes of
+  // problems:
+  //
+  //  - Relocation entry bugs, the two algorithms are unlikely to have the same
+  //    exact bug.
+  //
+  //  - Relaxation issues, where we forget to relax something.
+  //
+  //  - Input errors, where something cannot be correctly encoded. 'as' allows
+  //    these through in many cases.
+
+  void addRelocation(const MCSectionData *SD,
+                     object::macho::RelocationEntry &MRE) {
+    Relocations[SD].push_back(MRE);
+  }
+
+  void RecordScatteredRelocation(const MCAssembler &Asm,
+                                 const MCAsmLayout &Layout,
+                                 const MCFragment *Fragment,
+                                 const MCFixup &Fixup, MCValue Target,
+                                 unsigned Log2Size,
+                                 uint64_t &FixedValue);
+
+  void RecordTLVPRelocation(const MCAssembler &Asm,
+                            const MCAsmLayout &Layout,
+                            const MCFragment *Fragment,
+                            const MCFixup &Fixup, MCValue Target,
+                            uint64_t &FixedValue);
+
+  void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
+                        const MCFragment *Fragment, const MCFixup &Fixup,
+                        MCValue Target, uint64_t &FixedValue);
+
+  void BindIndirectSymbols(MCAssembler &Asm);
+
+  /// 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 ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable,
+                          std::vector<MachSymbolData> &LocalSymbolData,
+                          std::vector<MachSymbolData> &ExternalSymbolData,
+                          std::vector<MachSymbolData> &UndefinedSymbolData);
+
+  void computeSectionAddresses(const MCAssembler &Asm,
+                               const MCAsmLayout &Layout);
+
+  void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout);
+
+  virtual bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
+                                                      const MCSymbolData &DataA,
+                                                      const MCFragment &FB,
+                                                      bool InSet,
+                                                      bool IsPCRel) const;
+
+  void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
+};
+
+
 /// \brief Construct a new Mach-O writer instance.
 ///
 /// This routine takes ownership of the target writer subclass.