include/llvm/IR/GlobalObject.h

   1 //===-- llvm/GlobalObject.h - Class to represent global objects -*- 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 // This represents an independent object. That is, a function or a global
  10 // variable, but not an alias.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_IR_GLOBALOBJECT_H
  15 #define LLVM_IR_GLOBALOBJECT_H
  16
  17 #include "llvm/ADT/StringRef.h"
  18 #include "llvm/IR/GlobalValue.h"
  19 #include "llvm/IR/Value.h"
  20 #include "llvm/Support/Alignment.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     MaybeAlign Align = decodeMaybeAlign(AlignmentData);
  63     return Align ? Align->value() : 0;
  64   }
  65
  66   /// FIXME: Remove this setter once the migration to MaybeAlign is over.
  67   LLVM_ATTRIBUTE_DEPRECATED(void setAlignment(unsigned Align),
  68                             "Please use `void setAlignment(MaybeAlign Align)`");
  69   void setAlignment(MaybeAlign Align);
  70
  71   unsigned getGlobalObjectSubClassData() const {
  72     unsigned ValueData = getGlobalValueSubClassData();
  73     return ValueData >> GlobalObjectBits;
  74   }
  75
  76   void setGlobalObjectSubClassData(unsigned Val) {
  77     unsigned OldData = getGlobalValueSubClassData();
  78     setGlobalValueSubClassData((OldData & GlobalObjectMask) |
  79                                (Val << GlobalObjectBits));
  80     assert(getGlobalObjectSubClassData() == Val && "representation error");
  81   }
  82
  83   /// Check if this global has a custom object file section.
  84   ///
  85   /// This is more efficient than calling getSection() and checking for an empty
  86   /// string.
  87   bool hasSection() const {
  88     return getGlobalValueSubClassData() & (1 << HasSectionHashEntryBit);
  89   }
  90
  91   /// Get the custom section of this global if it has one.
  92   ///
  93   /// If this global does not have a custom section, this will be empty and the
  94   /// default object file section (.text, .data, etc) will be used.
  95   StringRef getSection() const {
  96     return hasSection() ? getSectionImpl() : StringRef();
  97   }
  98
  99   /// Change the section for this global.
 100   ///
 101   /// Setting the section to the empty string tells LLVM to choose an
 102   /// appropriate default object file section.
 103   void setSection(StringRef S);
 104
 105   bool hasComdat() const { return getComdat() != nullptr; }
 106   const Comdat *getComdat() const { return ObjComdat; }
 107   Comdat *getComdat() { return ObjComdat; }
 108   void setComdat(Comdat *C) { ObjComdat = C; }
 109
 110   /// Check if this has any metadata.
 111   bool hasMetadata() const { return hasMetadataHashEntry(); }
 112
 113   /// Check if this has any metadata of the given kind.
 114   bool hasMetadata(unsigned KindID) const {
 115     return getMetadata(KindID) != nullptr;
 116   }
 117   bool hasMetadata(StringRef Kind) const {
 118     return getMetadata(Kind) != nullptr;
 119   }
 120
 121   /// Get the current metadata attachments for the given kind, if any.
 122   ///
 123   /// These functions require that the function have at most a single attachment
 124   /// of the given kind, and return \c nullptr if such an attachment is missing.
 125   /// @{
 126   MDNode *getMetadata(unsigned KindID) const;
 127   MDNode *getMetadata(StringRef Kind) const;
 128   /// @}
 129
 130   /// Appends all attachments with the given ID to \c MDs in insertion order.
 131   /// If the global has no attachments with the given ID, or if ID is invalid,
 132   /// leaves MDs unchanged.
 133   /// @{
 134   void getMetadata(unsigned KindID, SmallVectorImpl<MDNode *> &MDs) const;
 135   void getMetadata(StringRef Kind, SmallVectorImpl<MDNode *> &MDs) const;
 136   /// @}
 137
 138   /// Set a particular kind of metadata attachment.
 139   ///
 140   /// Sets the given attachment to \c MD, erasing it if \c MD is \c nullptr or
 141   /// replacing it if it already exists.
 142   /// @{
 143   void setMetadata(unsigned KindID, MDNode *MD);
 144   void setMetadata(StringRef Kind, MDNode *MD);
 145   /// @}
 146
 147   /// Add a metadata attachment.
 148   /// @{
 149   void addMetadata(unsigned KindID, MDNode &MD);
 150   void addMetadata(StringRef Kind, MDNode &MD);
 151   /// @}
 152
 153   /// Appends all attachments for the global to \c MDs, sorting by attachment
 154   /// ID. Attachments with the same ID appear in insertion order.
 155   void
 156   getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const;
 157
 158   /// Erase all metadata attachments with the given kind.
 159   ///
 160   /// \returns true if any metadata was removed.
 161   bool eraseMetadata(unsigned KindID);
 162
 163   /// Copy metadata from Src, adjusting offsets by Offset.
 164   void copyMetadata(const GlobalObject *Src, unsigned Offset);
 165
 166   void addTypeMetadata(unsigned Offset, Metadata *TypeID);
 167
 168 protected:
 169   void copyAttributesFrom(const GlobalObject *Src);
 170
 171 public:
 172   // Methods for support type inquiry through isa, cast, and dyn_cast:
 173   static bool classof(const Value *V) {
 174     return V->getValueID() == Value::FunctionVal ||
 175            V->getValueID() == Value::GlobalVariableVal;
 176   }
 177
 178   void clearMetadata();
 179
 180 private:
 181   void setGlobalObjectFlag(unsigned Bit, bool Val) {
 182     unsigned Mask = 1 << Bit;
 183     setGlobalValueSubClassData((~Mask & getGlobalValueSubClassData()) |
 184                                (Val ? Mask : 0u));
 185   }
 186
 187   bool hasMetadataHashEntry() const {
 188     return getGlobalValueSubClassData() & (1 << HasMetadataHashEntryBit);
 189   }
 190   void setHasMetadataHashEntry(bool HasEntry) {
 191     setGlobalObjectFlag(HasMetadataHashEntryBit, HasEntry);
 192   }
 193
 194   StringRef getSectionImpl() const;
 195 };
 196
 197 } // end namespace llvm
 198
 199 #endif // LLVM_IR_GLOBALOBJECT_H