lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.h

   1 //===----- MachOAtomGraphBuilder.h - MachO AtomGraph builder ----*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Generic MachO AtomGraph building code.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LIB_EXECUTIONENGINE_JITLINK_MACHOATOMGRAPHBUILDER_H
  14 #define LIB_EXECUTIONENGINE_JITLINK_MACHOATOMGRAPHBUILDER_H
  15
  16 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
  17
  18 #include "JITLinkGeneric.h"
  19
  20 #include "llvm/Object/MachO.h"
  21
  22 namespace llvm {
  23 namespace jitlink {
  24
  25 class MachOAtomGraphBuilder {
  26 public:
  27   virtual ~MachOAtomGraphBuilder();
  28   Expected<std::unique_ptr<AtomGraph>> buildGraph();
  29
  30 protected:
  31   using OffsetToAtomMap = std::map<JITTargetAddress, DefinedAtom *>;
  32
  33   class MachOSection {
  34   public:
  35     MachOSection() = default;
  36
  37     /// Create a MachO section with the given address and alignment.
  38     MachOSection(Section &GenericSection, JITTargetAddress Address,
  39                  unsigned Alignment)
  40         : Address(Address), GenericSection(&GenericSection),
  41           Alignment(Alignment) {}
  42
  43     /// Create a section without address, content or size (used for common
  44     /// symbol sections).
  45     MachOSection(Section &GenericSection) : GenericSection(&GenericSection) {}
  46
  47     Section &getGenericSection() const {
  48       assert(GenericSection && "Section is null");
  49       return *GenericSection;
  50     }
  51
  52     StringRef getName() const {
  53       assert(GenericSection && "No generic section attached");
  54       return GenericSection->getName();
  55     }
  56
  57     MachOSection &setContent(StringRef Content) {
  58       assert(!ContentPtr && !Size && "Content/zeroFill already set");
  59       ContentPtr = Content.data();
  60       Size = Content.size();
  61       return *this;
  62     }
  63
  64     MachOSection &setZeroFill(uint64_t Size) {
  65       assert(!ContentPtr && !this->Size && "Content/zeroFill already set");
  66       this->Size = Size;
  67       return *this;
  68     }
  69
  70     bool isZeroFill() const { return !ContentPtr; }
  71
  72     bool empty() const { return getSize() == 0; }
  73
  74     size_t getSize() const { return Size; }
  75
  76     StringRef getContent() const {
  77       assert(ContentPtr && "getContent() called on zero-fill section");
  78       return {ContentPtr, static_cast<size_t>(Size)};
  79     }
  80
  81     JITTargetAddress getAddress() const { return Address; }
  82
  83     unsigned getAlignment() const { return Alignment; }
  84
  85     MachOSection &setNoDeadStrip(bool NoDeadStrip) {
  86       this->NoDeadStrip = NoDeadStrip;
  87       return *this;
  88     }
  89
  90     bool isNoDeadStrip() const { return NoDeadStrip; }
  91
  92   private:
  93     JITTargetAddress Address = 0;
  94     Section *GenericSection = nullptr;
  95     const char *ContentPtr = nullptr;
  96     uint64_t Size = 0;
  97     unsigned Alignment = 0;
  98     bool NoDeadStrip = false;
  99   };
 100
 101   using CustomAtomizeFunction = std::function<Error(MachOSection &S)>;
 102
 103   MachOAtomGraphBuilder(const object::MachOObjectFile &Obj);
 104
 105   AtomGraph &getGraph() const { return *G; }
 106
 107   const object::MachOObjectFile &getObject() const { return Obj; }
 108
 109   void addCustomAtomizer(StringRef SectionName, CustomAtomizeFunction Atomizer);
 110
 111   virtual Error addRelocations() = 0;
 112
 113   /// Returns true if Atom A and Atom B are at a fixed offset from one another
 114   /// (i.e. if they're part of the same alt-entry chain).
 115   bool areLayoutLocked(const Atom &A, const Atom &B);
 116
 117 private:
 118   static unsigned getPointerSize(const object::MachOObjectFile &Obj);
 119   static support::endianness getEndianness(const object::MachOObjectFile &Obj);
 120
 121   MachOSection &getCommonSection();
 122
 123   Error parseSections();
 124   Error addNonCustomAtoms();
 125   Error addAtoms();
 126
 127   const object::MachOObjectFile &Obj;
 128   std::unique_ptr<AtomGraph> G;
 129   DenseMap<const DefinedAtom *, const DefinedAtom *> AltEntryStarts;
 130   DenseMap<unsigned, MachOSection> Sections;
 131   StringMap<CustomAtomizeFunction> CustomAtomizeFunctions;
 132   Optional<MachOSection> CommonSymbolsSection;
 133 };
 134
 135 } // end namespace jitlink
 136 } // end namespace llvm
 137
 138 #endif // LIB_EXECUTIONENGINE_JITLINK_MACHOATOMGRAPHBUILDER_H