1 //===-- llvm/GlobalValue.h - Class to represent a global value --*- 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 file is a common base class of all globally definable objects. As such, 11 // it is subclassed by GlobalVariable, GlobalAlias and by Function. This is 12 // used because you can do certain things with these global objects that you 13 // can't do to anything else. For example, use the address of one as a 14 // constant. 15 // 16 //===----------------------------------------------------------------------===// 17 18 #ifndef LLVM_GLOBALVALUE_H 19 #define LLVM_GLOBALVALUE_H 20 21 #include "llvm/Constant.h" 22 23 namespace llvm { 24 25 class PointerType; 26 class Module; 27 28 class GlobalValue : public Constant { 29 GlobalValue(const GlobalValue &); // do not implement 30 public: 31 /// @brief An enumeration for the kinds of linkage for global values. 32 enum LinkageTypes { 33 ExternalLinkage = 0,///< Externally visible function 34 AvailableExternallyLinkage, ///< Available for inspection, not emission. 35 LinkOnceAnyLinkage, ///< Keep one copy of function when linking (inline) 36 LinkOnceODRLinkage, ///< Same, but only replaced by something equivalent. 37 WeakAnyLinkage, ///< Keep one copy of named function when linking (weak) 38 WeakODRLinkage, ///< Same, but only replaced by something equivalent. 39 AppendingLinkage, ///< Special purpose, only applies to global arrays 40 InternalLinkage, ///< Rename collisions when linking (static functions). 41 PrivateLinkage, ///< Like Internal, but omit from symbol table. 42 LinkerPrivateLinkage, ///< Like Private, but linker removes. 43 LinkerPrivateWeakLinkage, ///< Like LinkerPrivate, but weak. 44 LinkerPrivateWeakDefAutoLinkage, ///< Like LinkerPrivateWeak, but possibly 45 /// hidden. 46 DLLImportLinkage, ///< Function to be imported from DLL 47 DLLExportLinkage, ///< Function to be accessible from DLL. 48 ExternalWeakLinkage,///< ExternalWeak linkage description. 49 CommonLinkage ///< Tentative definitions. 50 }; 51 52 /// @brief An enumeration for the kinds of visibility of global values. 53 enum VisibilityTypes { 54 DefaultVisibility = 0, ///< The GV is visible 55 HiddenVisibility, ///< The GV is hidden 56 ProtectedVisibility ///< The GV is protected 57 }; 58 59 protected: 60 GlobalValue(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps, 61 LinkageTypes linkage, const Twine &Name) 62 : Constant(ty, vty, Ops, NumOps), Linkage(linkage), 63 Visibility(DefaultVisibility), Alignment(0), UnnamedAddr(0), Parent(0) { 64 setName(Name); 65 } 66 67 // Note: VC++ treats enums as signed, so an extra bit is required to prevent 68 // Linkage and Visibility from turning into negative values. 69 LinkageTypes Linkage : 5; // The linkage of this global 70 unsigned Visibility : 2; // The visibility style of this global 71 unsigned Alignment : 16; // Alignment of this symbol, must be power of two 72 unsigned UnnamedAddr : 1; // This value's address is not significant 73 Module *Parent; // The containing module. 74 std::string Section; // Section to emit this into, empty mean default 75 public: 76 ~GlobalValue() { 77 removeDeadConstantUsers(); // remove any dead constants using this. 78 } 79 80 unsigned getAlignment() const { 81 return (1u << Alignment) >> 1; 82 } 83 void setAlignment(unsigned Align); 84 85 bool hasUnnamedAddr() const { return UnnamedAddr; } 86 void setUnnamedAddr(bool Val) { UnnamedAddr = Val; } 87 88 VisibilityTypes getVisibility() const { return VisibilityTypes(Visibility); } 89 bool hasDefaultVisibility() const { return Visibility == DefaultVisibility; } 90 bool hasHiddenVisibility() const { return Visibility == HiddenVisibility; } 91 bool hasProtectedVisibility() const { 92 return Visibility == ProtectedVisibility; 93 } 94 void setVisibility(VisibilityTypes V) { Visibility = V; } 95 96 bool hasSection() const { return !Section.empty(); } 97 const std::string &getSection() const { return Section; } 98 void setSection(StringRef S) { Section = S; } 99 100 /// If the usage is empty (except transitively dead constants), then this 101 /// global value can be safely deleted since the destructor will 102 /// delete the dead constants as well. 103 /// @brief Determine if the usage of this global value is empty except 104 /// for transitively dead constants. 105 bool use_empty_except_constants(); 106 107 /// getType - Global values are always pointers. 108 inline PointerType *getType() const { 109 return reinterpret_cast<PointerType*>(User::getType()); 110 } 111 112 static LinkageTypes getLinkOnceLinkage(bool ODR) { 113 return ODR ? LinkOnceODRLinkage : LinkOnceAnyLinkage; 114 } 115 static LinkageTypes getWeakLinkage(bool ODR) { 116 return ODR ? WeakODRLinkage : WeakAnyLinkage; 117 } 118 119 static bool isExternalLinkage(LinkageTypes Linkage) { 120 return Linkage == ExternalLinkage; 121 } 122 static bool isAvailableExternallyLinkage(LinkageTypes Linkage) { 123 return Linkage == AvailableExternallyLinkage; 124 } 125 static bool isLinkOnceLinkage(LinkageTypes Linkage) { 126 return Linkage == LinkOnceAnyLinkage || Linkage == LinkOnceODRLinkage; 127 } 128 static bool isWeakLinkage(LinkageTypes Linkage) { 129 return Linkage == WeakAnyLinkage || Linkage == WeakODRLinkage; 130 } 131 static bool isAppendingLinkage(LinkageTypes Linkage) { 132 return Linkage == AppendingLinkage; 133 } 134 static bool isInternalLinkage(LinkageTypes Linkage) { 135 return Linkage == InternalLinkage; 136 } 137 static bool isPrivateLinkage(LinkageTypes Linkage) { 138 return Linkage == PrivateLinkage; 139 } 140 static bool isLinkerPrivateLinkage(LinkageTypes Linkage) { 141 return Linkage == LinkerPrivateLinkage; 142 } 143 static bool isLinkerPrivateWeakLinkage(LinkageTypes Linkage) { 144 return Linkage == LinkerPrivateWeakLinkage; 145 } 146 static bool isLinkerPrivateWeakDefAutoLinkage(LinkageTypes Linkage) { 147 return Linkage == LinkerPrivateWeakDefAutoLinkage; 148 } 149 static bool isLocalLinkage(LinkageTypes Linkage) { 150 return isInternalLinkage(Linkage) || isPrivateLinkage(Linkage) || 151 isLinkerPrivateLinkage(Linkage) || isLinkerPrivateWeakLinkage(Linkage) || 152 isLinkerPrivateWeakDefAutoLinkage(Linkage); 153 } 154 static bool isDLLImportLinkage(LinkageTypes Linkage) { 155 return Linkage == DLLImportLinkage; 156 } 157 static bool isDLLExportLinkage(LinkageTypes Linkage) { 158 return Linkage == DLLExportLinkage; 159 } 160 static bool isExternalWeakLinkage(LinkageTypes Linkage) { 161 return Linkage == ExternalWeakLinkage; 162 } 163 static bool isCommonLinkage(LinkageTypes Linkage) { 164 return Linkage == CommonLinkage; 165 } 166 167 /// mayBeOverridden - Whether the definition of this global may be replaced 168 /// by something non-equivalent at link time. For example, if a function has 169 /// weak linkage then the code defining it may be replaced by different code. 170 static bool mayBeOverridden(LinkageTypes Linkage) { 171 return Linkage == WeakAnyLinkage || 172 Linkage == LinkOnceAnyLinkage || 173 Linkage == CommonLinkage || 174 Linkage == ExternalWeakLinkage || 175 Linkage == LinkerPrivateWeakLinkage || 176 Linkage == LinkerPrivateWeakDefAutoLinkage; 177 } 178 179 /// isWeakForLinker - Whether the definition of this global may be replaced at 180 /// link time. NB: Using this method outside of the code generators is almost 181 /// always a mistake: when working at the IR level use mayBeOverridden instead 182 /// as it knows about ODR semantics. 183 static bool isWeakForLinker(LinkageTypes Linkage) { 184 return Linkage == AvailableExternallyLinkage || 185 Linkage == WeakAnyLinkage || 186 Linkage == WeakODRLinkage || 187 Linkage == LinkOnceAnyLinkage || 188 Linkage == LinkOnceODRLinkage || 189 Linkage == CommonLinkage || 190 Linkage == ExternalWeakLinkage || 191 Linkage == LinkerPrivateWeakLinkage || 192 Linkage == LinkerPrivateWeakDefAutoLinkage; 193 } 194 195 bool hasExternalLinkage() const { return isExternalLinkage(Linkage); } 196 bool hasAvailableExternallyLinkage() const { 197 return isAvailableExternallyLinkage(Linkage); 198 } 199 bool hasLinkOnceLinkage() const { 200 return isLinkOnceLinkage(Linkage); 201 } 202 bool hasWeakLinkage() const { 203 return isWeakLinkage(Linkage); 204 } 205 bool hasAppendingLinkage() const { return isAppendingLinkage(Linkage); } 206 bool hasInternalLinkage() const { return isInternalLinkage(Linkage); } 207 bool hasPrivateLinkage() const { return isPrivateLinkage(Linkage); } 208 bool hasLinkerPrivateLinkage() const { return isLinkerPrivateLinkage(Linkage); } 209 bool hasLinkerPrivateWeakLinkage() const { 210 return isLinkerPrivateWeakLinkage(Linkage); 211 } 212 bool hasLinkerPrivateWeakDefAutoLinkage() const { 213 return isLinkerPrivateWeakDefAutoLinkage(Linkage); 214 } 215 bool hasLocalLinkage() const { return isLocalLinkage(Linkage); } 216 bool hasDLLImportLinkage() const { return isDLLImportLinkage(Linkage); } 217 bool hasDLLExportLinkage() const { return isDLLExportLinkage(Linkage); } 218 bool hasExternalWeakLinkage() const { return isExternalWeakLinkage(Linkage); } 219 bool hasCommonLinkage() const { return isCommonLinkage(Linkage); } 220 221 void setLinkage(LinkageTypes LT) { Linkage = LT; } 222 LinkageTypes getLinkage() const { return Linkage; } 223 224 bool mayBeOverridden() const { return mayBeOverridden(Linkage); } 225 226 bool isWeakForLinker() const { return isWeakForLinker(Linkage); } 227 228 /// copyAttributesFrom - copy all additional attributes (those not needed to 229 /// create a GlobalValue) from the GlobalValue Src to this one. 230 virtual void copyAttributesFrom(const GlobalValue *Src); 231 232 /// @name Materialization 233 /// Materialization is used to construct functions only as they're needed. This 234 /// is useful to reduce memory usage in LLVM or parsing work done by the 235 /// BitcodeReader to load the Module. 236 /// @{ 237 238 /// isMaterializable - If this function's Module is being lazily streamed in 239 /// functions from disk or some other source, this method can be used to check 240 /// to see if the function has been read in yet or not. 241 bool isMaterializable() const; 242 243 /// isDematerializable - Returns true if this function was loaded from a 244 /// GVMaterializer that's still attached to its Module and that knows how to 245 /// dematerialize the function. 246 bool isDematerializable() const; 247 248 /// Materialize - make sure this GlobalValue is fully read. If the module is 249 /// corrupt, this returns true and fills in the optional string with 250 /// information about the problem. If successful, this returns false. 251 bool Materialize(std::string *ErrInfo = 0); 252 253 /// Dematerialize - If this GlobalValue is read in, and if the GVMaterializer 254 /// supports it, release the memory for the function, and set it up to be 255 /// materialized lazily. If !isDematerializable(), this method is a noop. 256 void Dematerialize(); 257 258 /// @} 259 260 /// Override from Constant class. 261 virtual void destroyConstant(); 262 263 /// isDeclaration - Return true if the primary definition of this global 264 /// value is outside of the current translation unit. 265 bool isDeclaration() const; 266 267 /// removeFromParent - This method unlinks 'this' from the containing module, 268 /// but does not delete it. 269 virtual void removeFromParent() = 0; 270 271 /// eraseFromParent - This method unlinks 'this' from the containing module 272 /// and deletes it. 273 virtual void eraseFromParent() = 0; 274 275 /// getParent - Get the module that this global value is contained inside 276 /// of... 277 inline Module *getParent() { return Parent; } 278 inline const Module *getParent() const { return Parent; } 279 280 // Methods for support type inquiry through isa, cast, and dyn_cast: 281 static inline bool classof(const GlobalValue *) { return true; } 282 static inline bool classof(const Value *V) { 283 return V->getValueID() == Value::FunctionVal || 284 V->getValueID() == Value::GlobalVariableVal || 285 V->getValueID() == Value::GlobalAliasVal; 286 } 287 }; 288 289 } // End llvm namespace 290 291 #endif 292
