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