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//===-- llvm/GlobalVariable.h - GlobalVariable class ------------*- 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 contains the declaration of the GlobalVariable class, which
// represents a single global variable (or constant) in the VM.
// Global variables are constant pointers that refer to hunks of space that are
// allocated by either the VM, or by the linker in a static compiler. A global
// variable may have an intial value, which is copied into the executables .data
// area. Global Constants are required to have initializers.
#include "llvm/GlobalValue.h"
namespace llvm {
class Module;
class Constant;
class PointerType;
template<typename SC> struct ilist_traits;
template<typename ValueSubClass, typename ItemParentClass, typename SymTabClass,
typename SubClass> class SymbolTableListTraits;
class GlobalVariable : public GlobalValue {
friend class SymbolTableListTraits<GlobalVariable, Module, Module,
ilist_traits<GlobalVariable> >;
void setParent(Module *parent);
GlobalVariable *Prev, *Next;
void setNext(GlobalVariable *N) { Next = N; }
void setPrev(GlobalVariable *N) { Prev = N; }
bool isConstantGlobal; // Is this a global constant?
Use Initializer;
/// GlobalVariable ctor - If a parent module is specified, the global is
/// automatically inserted into the end of the specified modules global list.
GlobalVariable(const Type *Ty, bool isConstant, LinkageTypes Linkage,
Constant *Initializer = 0, const std::string &Name = "",
Module *Parent = 0);
/// isExternal - Is this global variable lacking an initializer? If so, the
/// global variable is defined in some other translation unit, and is thus
/// externally defined here.
virtual bool isExternal() const { return getNumOperands() == 0; }
/// hasInitializer - Unless a global variable isExternal(), it has an
/// initializer. The initializer for the global variable/constant is held by
/// Initializer if an initializer is specified.
inline bool hasInitializer() const { return !isExternal(); }
/// getInitializer - Return the initializer for this global variable. It is
/// illegal to call this method if the global is external, because we cannot
/// tell what the value is initialized to!
inline Constant *getInitializer() const {
assert(hasInitializer() && "GV doesn't have initializer!");
return reinterpret_cast<Constant*>(Initializer.get());
inline Constant *getInitializer() {
assert(hasInitializer() && "GV doesn't have initializer!");
return reinterpret_cast<Constant*>(Initializer.get());
inline void setInitializer(Constant *CPV) {
if (CPV == 0) {
if (hasInitializer()) {
NumOperands = 0;
} else {
if (!hasInitializer())
NumOperands = 1;
// getNext/Prev - Return the next or previous global variable in the list.
GlobalVariable *getNext() { return Next; }
const GlobalVariable *getNext() const { return Next; }
GlobalVariable *getPrev() { return Prev; }
const GlobalVariable *getPrev() const { return Prev; }
/// If the value is a global constant, its value is immutable throughout the
/// runtime execution of the program. Assigning a value into the constant
/// leads to undefined behavior.
bool isConstant() const { return isConstantGlobal; }
void setConstant(bool Value) { isConstantGlobal = Value; }
/// removeFromParent - This method unlinks 'this' from the containing module,
/// but does not delete it.
void removeFromParent();
/// eraseFromParent - This method unlinks 'this' from the containing module
/// and deletes it.
void eraseFromParent();
/// Override Constant's implementation of this method so we can
/// replace constant initializers.
virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
virtual void print(std::ostream &OS) const;
// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const GlobalVariable *) { return true; }
static inline bool classof(const Value *V) {
return V->getValueType() == Value::GlobalVariableVal;
} // End llvm namespace