include/llvm/IR/GlobalObject.h

   1 //===-- llvm/GlobalObject.h - Class to represent global objects -*- 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 // This represents an independent object. That is, a function or a global
  11 // variable, but not an alias.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_IR_GLOBALOBJECT_H
  16 #define LLVM_IR_GLOBALOBJECT_H
  17
  18 #include "llvm/ADT/StringRef.h"
  19 #include "llvm/IR/GlobalValue.h"
  20 #include "llvm/IR/Value.h"
  21 #include <string>
  22 #include <utility>
  23
  24 namespace llvm {
  25
  26 class Comdat;
  27 class MDNode;
  28 class Metadata;
  29
  30 class GlobalObject : public GlobalValue {
  31 protected:
  32   GlobalObject(Type *Ty, ValueTy VTy, Use *Ops, unsigned NumOps,
  33                LinkageTypes Linkage, const Twine &Name,
  34                unsigned AddressSpace = 0)
  35       : GlobalValue(Ty, VTy, Ops, NumOps, Linkage, Name, AddressSpace),
  36         ObjComdat(nullptr) {
  37     setGlobalValueSubClassData(0);
  38   }
  39
  40   Comdat *ObjComdat;
  41   enum {
  42     LastAlignmentBit = 4,
  43     HasMetadataHashEntryBit,
  44     HasSectionHashEntryBit,
  45
  46     GlobalObjectBits,
  47   };
  48   static const unsigned GlobalObjectSubClassDataBits =
  49       GlobalValueSubClassDataBits - GlobalObjectBits;
  50
  51 private:
  52   static const unsigned AlignmentBits = LastAlignmentBit + 1;
  53   static const unsigned AlignmentMask = (1 << AlignmentBits) - 1;
  54   static const unsigned GlobalObjectMask = (1 << GlobalObjectBits) - 1;
  55
  56 public:
  57   GlobalObject(const GlobalObject &) = delete;
  58
  59   unsigned getAlignment() const {
  60     unsigned Data = getGlobalValueSubClassData();
  61     unsigned AlignmentData = Data & AlignmentMask;
  62     return (1u << AlignmentData) >> 1;
  63   }
  64   void setAlignment(unsigned Align);
  65
  66   unsigned getGlobalObjectSubClassData() const {
  67     unsigned ValueData = getGlobalValueSubClassData();
  68     return ValueData >> GlobalObjectBits;
  69   }
  70
  71   void setGlobalObjectSubClassData(unsigned Val) {
  72     unsigned OldData = getGlobalValueSubClassData();
  73     setGlobalValueSubClassData((OldData & GlobalObjectMask) |
  74                                (Val << GlobalObjectBits));
  75     assert(getGlobalObjectSubClassData() == Val && "representation error");
  76   }
  77
  78   /// Check if this global has a custom object file section.
  79   ///
  80   /// This is more efficient than calling getSection() and checking for an empty
  81   /// string.
  82   bool hasSection() const {
  83     return getGlobalValueSubClassData() & (1 << HasSectionHashEntryBit);
  84   }
  85
  86   /// Get the custom section of this global if it has one.
  87   ///
  88   /// If this global does not have a custom section, this will be empty and the
  89   /// default object file section (.text, .data, etc) will be used.
  90   StringRef getSection() const {
  91     return hasSection() ? getSectionImpl() : StringRef();
  92   }
  93
  94   /// Change the section for this global.
  95   ///
  96   /// Setting the section to the empty string tells LLVM to choose an
  97   /// appropriate default object file section.
  98   void setSection(StringRef S);
  99
 100   bool hasComdat() const { return getComdat() != nullptr; }
 101   const Comdat *getComdat() const { return ObjComdat; }
 102   Comdat *getComdat() { return ObjComdat; }
 103   void setComdat(Comdat *C) { ObjComdat = C; }
 104
 105   /// Check if this has any metadata.
 106   bool hasMetadata() const { return hasMetadataHashEntry(); }
 107
 108   /// Check if this has any metadata of the given kind.
 109   bool hasMetadata(unsigned KindID) const {
 110     return getMetadata(KindID) != nullptr;
 111   }
 112   bool hasMetadata(StringRef Kind) const {
 113     return getMetadata(Kind) != nullptr;
 114   }
 115
 116   /// Get the current metadata attachments for the given kind, if any.
 117   ///
 118   /// These functions require that the function have at most a single attachment
 119   /// of the given kind, and return \c nullptr if such an attachment is missing.
 120   /// @{
 121   MDNode *getMetadata(unsigned KindID) const;
 122   MDNode *getMetadata(StringRef Kind) const;
 123   /// @}
 124
 125   /// Appends all attachments with the given ID to \c MDs in insertion order.
 126   /// If the global has no attachments with the given ID, or if ID is invalid,
 127   /// leaves MDs unchanged.
 128   /// @{
 129   void getMetadata(unsigned KindID, SmallVectorImpl<MDNode *> &MDs) const;
 130   void getMetadata(StringRef Kind, SmallVectorImpl<MDNode *> &MDs) const;
 131   /// @}
 132
 133   /// Set a particular kind of metadata attachment.
 134   ///
 135   /// Sets the given attachment to \c MD, erasing it if \c MD is \c nullptr or
 136   /// replacing it if it already exists.
 137   /// @{
 138   void setMetadata(unsigned KindID, MDNode *MD);
 139   void setMetadata(StringRef Kind, MDNode *MD);
 140   /// @}
 141
 142   /// Add a metadata attachment.
 143   /// @{
 144   void addMetadata(unsigned KindID, MDNode &MD);
 145   void addMetadata(StringRef Kind, MDNode &MD);
 146   /// @}
 147
 148   /// Appends all attachments for the global to \c MDs, sorting by attachment
 149   /// ID. Attachments with the same ID appear in insertion order.
 150   void
 151   getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const;
 152
 153   /// Erase all metadata attachments with the given kind.
 154   ///
 155   /// \returns true if any metadata was removed.
 156   bool eraseMetadata(unsigned KindID);
 157
 158   /// Copy metadata from Src, adjusting offsets by Offset.
 159   void copyMetadata(const GlobalObject *Src, unsigned Offset);
 160
 161   void addTypeMetadata(unsigned Offset, Metadata *TypeID);
 162
 163 protected:
 164   void copyAttributesFrom(const GlobalObject *Src);
 165
 166 public:
 167   // Methods for support type inquiry through isa, cast, and dyn_cast:
 168   static bool classof(const Value *V) {
 169     return V->getValueID() == Value::FunctionVal ||
 170            V->getValueID() == Value::GlobalVariableVal;
 171   }
 172
 173   void clearMetadata();
 174
 175 private:
 176   void setGlobalObjectFlag(unsigned Bit, bool Val) {
 177     unsigned Mask = 1 << Bit;
 178     setGlobalValueSubClassData((~Mask & getGlobalValueSubClassData()) |
 179                                (Val ? Mask : 0u));
 180   }
 181
 182   bool hasMetadataHashEntry() const {
 183     return getGlobalValueSubClassData() & (1 << HasMetadataHashEntryBit);
 184   }
 185   void setHasMetadataHashEntry(bool HasEntry) {
 186     setGlobalObjectFlag(HasMetadataHashEntryBit, HasEntry);
 187   }
 188
 189   StringRef getSectionImpl() const;
 190 };
 191
 192 } // end namespace llvm
 193
 194 #endif // LLVM_IR_GLOBALOBJECT_H