//===-- llvm/GlobalValue.h - Class to represent a global value --*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file was developed by the LLVM research group and is distributed under // the University of Illinois Open Source License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file is a common base class of all globally definable objects. As such, // it is subclassed by GlobalVariable and by Function. This is used because you // can do certain things with these global objects that you can't do to anything // else. For example, use the address of one as a constant. // //===----------------------------------------------------------------------===// #ifndef LLVM_GLOBALVALUE_H #define LLVM_GLOBALVALUE_H #include "llvm/Constant.h" namespace llvm { class PointerType; class Module; class GlobalValue : public Constant { GlobalValue(const GlobalValue &); // do not implement public: enum LinkageTypes { ExternalLinkage, /// Externally visible function LinkOnceLinkage, /// Keep one copy of named function when linking (inline) WeakLinkage, /// Keep one copy of named function when linking (weak) AppendingLinkage, /// Special purpose, only applies to global arrays InternalLinkage, /// Rename collisions when linking (static functions) GhostLinkage /// Stand-in functions for streaming fns from BC files }; protected: GlobalValue(const Type *Ty, ValueTy vty, Use *Ops, unsigned NumOps, LinkageTypes linkage, const std::string &name = "") : Constant(Ty, vty, Ops, NumOps, name), Linkage(linkage), Parent(0) { } LinkageTypes Linkage; // The linkage of this global Module *Parent; public: ~GlobalValue() { removeDeadConstantUsers(); // remove any dead constants using this. } /// If the usage is empty (except transitively dead constants), then this /// global value can can be safely deleted since the destructor will /// delete the dead constants as well. /// @brief Determine if the usage of this global value is empty except /// for transitively dead constants. bool use_empty_except_constants(); /// getType - Global values are always pointers. inline const PointerType *getType() const { return reinterpret_cast<const PointerType*>(User::getType()); } bool hasExternalLinkage() const { return Linkage == ExternalLinkage; } bool hasLinkOnceLinkage() const { return Linkage == LinkOnceLinkage; } bool hasWeakLinkage() const { return Linkage == WeakLinkage; } bool hasAppendingLinkage() const { return Linkage == AppendingLinkage; } bool hasInternalLinkage() const { return Linkage == InternalLinkage; } void setLinkage(LinkageTypes LT) { Linkage = LT; } LinkageTypes getLinkage() const { return Linkage; } /// hasNotBeenReadFromBytecode - If a module provider is being used to lazily /// stream in functions from disk, this method can be used to check to see if /// the function has been read in yet or not. Unless you are working on the /// JIT or something else that streams stuff in lazily, you don't need to /// worry about this. bool hasNotBeenReadFromBytecode() const { return Linkage == GhostLinkage; } /// Override from Constant class. No GlobalValue's are null values so this /// always returns false. virtual bool isNullValue() const { return false; } /// Override from Constant class. virtual void destroyConstant(); /// isExternal - Return true if the primary definition of this global value is /// outside of the current translation unit... virtual bool isExternal() const = 0; /// getParent - Get the module that this global value is contained inside /// of... inline Module *getParent() { return Parent; } inline const Module *getParent() const { return Parent; } /// removeDeadConstantUsers - If there are any dead constant users dangling /// off of this global value, remove them. This method is useful for clients /// that want to check to see if a global is unused, but don't want to deal /// with potentially dead constants hanging off of the globals. /// /// This method tries to make the global dead. If it detects a user that /// would prevent it from becoming completely dead, it gives up early, /// potentially leaving some dead constant users around. void removeDeadConstantUsers(); // Methods for support type inquiry through isa, cast, and dyn_cast: static inline bool classof(const GlobalValue *T) { return true; } static inline bool classof(const Value *V) { return V->getValueType() == Value::FunctionVal || V->getValueType() == Value::GlobalVariableVal; } }; } // End llvm namespace #endif