| //===-- llvm/GlobalValue.h - Class to represent a global value --*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file 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, GlobalAlias 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: |
| /// @brief An enumeration for the kinds of linkage for global values. |
| enum LinkageTypes { |
| ExternalLinkage = 0,///< Externally visible function |
| LinkOnceLinkage, ///< Keep one copy of 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) |
| DLLImportLinkage, ///< Function to be imported from DLL |
| DLLExportLinkage, ///< Function to be accessible from DLL |
| ExternalWeakLinkage,///< ExternalWeak linkage description |
| GhostLinkage ///< Stand-in functions for streaming fns from BC files |
| }; |
| |
| /// @brief An enumeration for the kinds of visibility of global values. |
| enum VisibilityTypes { |
| DefaultVisibility = 0, ///< The GV is visible |
| HiddenVisibility, ///< The GV is hidden |
| ProtectedVisibility ///< The GV is protected |
| }; |
| |
| protected: |
| GlobalValue(const Type *Ty, ValueTy vty, Use *Ops, unsigned NumOps, |
| LinkageTypes linkage, const std::string &name = "") |
| : Constant(Ty, vty, Ops, NumOps), Parent(0), |
| Linkage(linkage), Visibility(DefaultVisibility), Alignment(0) { |
| if (!name.empty()) setName(name); |
| } |
| |
| Module *Parent; |
| // Note: VC++ treats enums as signed, so an extra bit is required to prevent |
| // Linkage and Visibility from turning into negative values. |
| LinkageTypes Linkage : 5; // The linkage of this global |
| unsigned Visibility : 2; // The visibility style of this global |
| unsigned Alignment : 16; // Alignment of this symbol, must be power of two |
| std::string Section; // Section to emit this into, empty mean default |
| public: |
| ~GlobalValue() { |
| removeDeadConstantUsers(); // remove any dead constants using this. |
| } |
| |
| unsigned getAlignment() const { return Alignment; } |
| void setAlignment(unsigned Align) { |
| assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!"); |
| Alignment = Align; |
| } |
| |
| VisibilityTypes getVisibility() const { return VisibilityTypes(Visibility); } |
| bool hasHiddenVisibility() const { return Visibility == HiddenVisibility; } |
| bool hasProtectedVisibility() const { |
| return Visibility == ProtectedVisibility; |
| } |
| void setVisibility(VisibilityTypes V) { Visibility = V; } |
| |
| bool hasSection() const { return !Section.empty(); } |
| const std::string &getSection() const { return Section; } |
| void setSection(const std::string &S) { Section = S; } |
| |
| /// 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; } |
| bool hasDLLImportLinkage() const { return Linkage == DLLImportLinkage; } |
| bool hasDLLExportLinkage() const { return Linkage == DLLExportLinkage; } |
| bool hasExternalWeakLinkage() const { return Linkage == ExternalWeakLinkage; } |
| void setLinkage(LinkageTypes LT) { Linkage = LT; } |
| LinkageTypes getLinkage() const { return Linkage; } |
| |
| /// hasNotBeenReadFromBitcode - 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 hasNotBeenReadFromBitcode() 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(); |
| |
| /// isDeclaration - Return true if the primary definition of this global |
| /// value is outside of the current translation unit... |
| virtual bool isDeclaration() 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. |
| void removeDeadConstantUsers(); |
| |
| // Methods for support type inquiry through isa, cast, and dyn_cast: |
| static inline bool classof(const GlobalValue *) { return true; } |
| static inline bool classof(const Value *V) { |
| return V->getValueID() == Value::FunctionVal || |
| V->getValueID() == Value::GlobalVariableVal || |
| V->getValueID() == Value::GlobalAliasVal; |
| } |
| }; |
| |
| } // End llvm namespace |
| |
| #endif |