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), Parent(0), 63 Linkage(linkage), Visibility(DefaultVisibility), Alignment(0), 64 UnnamedAddr(0) { 65 setName(Name); 66 } 67 68 Module *Parent; 69 // Note: VC++ treats enums as signed, so an extra bit is required to prevent 70 // Linkage and Visibility from turning into negative values. 71 LinkageTypes Linkage : 5; // The linkage of this global 72 unsigned Visibility : 2; // The visibility style of this global 73 unsigned Alignment : 16; // Alignment of this symbol, must be power of two 74 unsigned UnnamedAddr : 1; // This value's address is not significant 75 std::string Section; // Section to emit this into, empty mean default 76 public: 77 ~GlobalValue() { 78 removeDeadConstantUsers(); // remove any dead constants using this. 79 } 80 81 unsigned getAlignment() const { 82 return (1u << Alignment) >> 1; 83 } 84 void setAlignment(unsigned Align); 85 86 bool hasUnnamedAddr() const { return UnnamedAddr; } 87 void setUnnamedAddr(bool Val) { UnnamedAddr = Val; } 88 89 VisibilityTypes getVisibility() const { return VisibilityTypes(Visibility); } 90 bool hasDefaultVisibility() const { return Visibility == DefaultVisibility; } 91 bool hasHiddenVisibility() const { return Visibility == HiddenVisibility; } 92 bool hasProtectedVisibility() const { 93 return Visibility == ProtectedVisibility; 94 } 95 void setVisibility(VisibilityTypes V) { Visibility = V; } 96 97 bool hasSection() const { return !Section.empty(); } 98 const std::string &getSection() const { return Section; } 99 void setSection(StringRef S) { Section = S; } 100 101 /// If the usage is empty (except transitively dead constants), then this 102 /// global value can be safely deleted since the destructor will 103 /// delete the dead constants as well. 104 /// @brief Determine if the usage of this global value is empty except 105 /// for transitively dead constants. 106 bool use_empty_except_constants(); 107 108 /// getType - Global values are always pointers. 109 inline PointerType *getType() const { 110 return reinterpret_cast<PointerType*>(User::getType()); 111 } 112 113 static LinkageTypes getLinkOnceLinkage(bool ODR) { 114 return ODR ? LinkOnceODRLinkage : LinkOnceAnyLinkage; 115 } 116 static LinkageTypes getWeakLinkage(bool ODR) { 117 return ODR ? WeakODRLinkage : WeakAnyLinkage; 118 } 119 120 static bool isExternalLinkage(LinkageTypes Linkage) { 121 return Linkage == ExternalLinkage; 122 } 123 static bool isAvailableExternallyLinkage(LinkageTypes Linkage) { 124 return Linkage == AvailableExternallyLinkage; 125 } 126 static bool isLinkOnceLinkage(LinkageTypes Linkage) { 127 return Linkage == LinkOnceAnyLinkage || Linkage == LinkOnceODRLinkage; 128 } 129 static bool isWeakLinkage(LinkageTypes Linkage) { 130 return Linkage == WeakAnyLinkage || Linkage == WeakODRLinkage; 131 } 132 static bool isAppendingLinkage(LinkageTypes Linkage) { 133 return Linkage == AppendingLinkage; 134 } 135 static bool isInternalLinkage(LinkageTypes Linkage) { 136 return Linkage == InternalLinkage; 137 } 138 static bool isPrivateLinkage(LinkageTypes Linkage) { 139 return Linkage == PrivateLinkage; 140 } 141 static bool isLinkerPrivateLinkage(LinkageTypes Linkage) { 142 return Linkage == LinkerPrivateLinkage; 143 } 144 static bool isLinkerPrivateWeakLinkage(LinkageTypes Linkage) { 145 return Linkage == LinkerPrivateWeakLinkage; 146 } 147 static bool isLinkerPrivateWeakDefAutoLinkage(LinkageTypes Linkage) { 148 return Linkage == LinkerPrivateWeakDefAutoLinkage; 149 } 150 static bool isLocalLinkage(LinkageTypes Linkage) { 151 return isInternalLinkage(Linkage) || isPrivateLinkage(Linkage) || 152 isLinkerPrivateLinkage(Linkage) || isLinkerPrivateWeakLinkage(Linkage) || 153 isLinkerPrivateWeakDefAutoLinkage(Linkage); 154 } 155 static bool isDLLImportLinkage(LinkageTypes Linkage) { 156 return Linkage == DLLImportLinkage; 157 } 158 static bool isDLLExportLinkage(LinkageTypes Linkage) { 159 return Linkage == DLLExportLinkage; 160 } 161 static bool isExternalWeakLinkage(LinkageTypes Linkage) { 162 return Linkage == ExternalWeakLinkage; 163 } 164 static bool isCommonLinkage(LinkageTypes Linkage) { 165 return Linkage == CommonLinkage; 166 } 167 168 /// mayBeOverridden - Whether the definition of this global may be replaced 169 /// by something non-equivalent at link time. For example, if a function has 170 /// weak linkage then the code defining it may be replaced by different code. 171 static bool mayBeOverridden(LinkageTypes Linkage) { 172 return Linkage == WeakAnyLinkage || 173 Linkage == LinkOnceAnyLinkage || 174 Linkage == CommonLinkage || 175 Linkage == ExternalWeakLinkage || 176 Linkage == LinkerPrivateWeakLinkage || 177 Linkage == LinkerPrivateWeakDefAutoLinkage; 178 } 179 180 /// isWeakForLinker - Whether the definition of this global may be replaced at 181 /// link time. NB: Using this method outside of the code generators is almost 182 /// always a mistake: when working at the IR level use mayBeOverridden instead 183 /// as it knows about ODR semantics. 184 static bool isWeakForLinker(LinkageTypes Linkage) { 185 return Linkage == AvailableExternallyLinkage || 186 Linkage == WeakAnyLinkage || 187 Linkage == WeakODRLinkage || 188 Linkage == LinkOnceAnyLinkage || 189 Linkage == LinkOnceODRLinkage || 190 Linkage == CommonLinkage || 191 Linkage == ExternalWeakLinkage || 192 Linkage == LinkerPrivateWeakLinkage || 193 Linkage == LinkerPrivateWeakDefAutoLinkage; 194 } 195 196 bool hasExternalLinkage() const { return isExternalLinkage(Linkage); } 197 bool hasAvailableExternallyLinkage() const { 198 return isAvailableExternallyLinkage(Linkage); 199 } 200 bool hasLinkOnceLinkage() const { 201 return isLinkOnceLinkage(Linkage); 202 } 203 bool hasWeakLinkage() const { 204 return isWeakLinkage(Linkage); 205 } 206 bool hasAppendingLinkage() const { return isAppendingLinkage(Linkage); } 207 bool hasInternalLinkage() const { return isInternalLinkage(Linkage); } 208 bool hasPrivateLinkage() const { return isPrivateLinkage(Linkage); } 209 bool hasLinkerPrivateLinkage() const { return isLinkerPrivateLinkage(Linkage); } 210 bool hasLinkerPrivateWeakLinkage() const { 211 return isLinkerPrivateWeakLinkage(Linkage); 212 } 213 bool hasLinkerPrivateWeakDefAutoLinkage() const { 214 return isLinkerPrivateWeakDefAutoLinkage(Linkage); 215 } 216 bool hasLocalLinkage() const { return isLocalLinkage(Linkage); } 217 bool hasDLLImportLinkage() const { return isDLLImportLinkage(Linkage); } 218 bool hasDLLExportLinkage() const { return isDLLExportLinkage(Linkage); } 219 bool hasExternalWeakLinkage() const { return isExternalWeakLinkage(Linkage); } 220 bool hasCommonLinkage() const { return isCommonLinkage(Linkage); } 221 222 void setLinkage(LinkageTypes LT) { Linkage = LT; } 223 LinkageTypes getLinkage() const { return Linkage; } 224 225 bool mayBeOverridden() const { return mayBeOverridden(Linkage); } 226 227 bool isWeakForLinker() const { return isWeakForLinker(Linkage); } 228 229 /// copyAttributesFrom - copy all additional attributes (those not needed to 230 /// create a GlobalValue) from the GlobalValue Src to this one. 231 virtual void copyAttributesFrom(const GlobalValue *Src); 232 233 /// @name Materialization 234 /// Materialization is used to construct functions only as they're needed. This 235 /// is useful to reduce memory usage in LLVM or parsing work done by the 236 /// BitcodeReader to load the Module. 237 /// @{ 238 239 /// isMaterializable - If this function's Module is being lazily streamed in 240 /// functions from disk or some other source, this method can be used to check 241 /// to see if the function has been read in yet or not. 242 bool isMaterializable() const; 243 244 /// isDematerializable - Returns true if this function was loaded from a 245 /// GVMaterializer that's still attached to its Module and that knows how to 246 /// dematerialize the function. 247 bool isDematerializable() const; 248 249 /// Materialize - make sure this GlobalValue is fully read. If the module is 250 /// corrupt, this returns true and fills in the optional string with 251 /// information about the problem. If successful, this returns false. 252 bool Materialize(std::string *ErrInfo = 0); 253 254 /// Dematerialize - If this GlobalValue is read in, and if the GVMaterializer 255 /// supports it, release the memory for the function, and set it up to be 256 /// materialized lazily. If !isDematerializable(), this method is a noop. 257 void Dematerialize(); 258 259 /// @} 260 261 /// Override from Constant class. 262 virtual void destroyConstant(); 263 264 /// isDeclaration - Return true if the primary definition of this global 265 /// value is outside of the current translation unit. 266 bool isDeclaration() const; 267 268 /// removeFromParent - This method unlinks 'this' from the containing module, 269 /// but does not delete it. 270 virtual void removeFromParent() = 0; 271 272 /// eraseFromParent - This method unlinks 'this' from the containing module 273 /// and deletes it. 274 virtual void eraseFromParent() = 0; 275 276 /// getParent - Get the module that this global value is contained inside 277 /// of... 278 inline Module *getParent() { return Parent; } 279 inline const Module *getParent() const { return Parent; } 280 281 // Methods for support type inquiry through isa, cast, and dyn_cast: 282 static inline bool classof(const GlobalValue *) { return true; } 283 static inline bool classof(const Value *V) { 284 return V->getValueID() == Value::FunctionVal || 285 V->getValueID() == Value::GlobalVariableVal || 286 V->getValueID() == Value::GlobalAliasVal; 287 } 288 }; 289 290 } // End llvm namespace 291 292 #endif 293
