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