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//===-- llvm/GlobalVariable.h - GlobalVariable class ------------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file contains the declaration of the GlobalVariable class, which
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// represents a single global variable (or constant) in the VM.
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// Global variables are constant pointers that refer to hunks of space that are
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// allocated by either the VM, or by the linker in a static compiler. A global
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// variable may have an intial value, which is copied into the executables .data
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// area. Global Constants are required to have initializers.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_GLOBAL_VARIABLE_H
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#define LLVM_GLOBAL_VARIABLE_H
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#include "llvm/GlobalValue.h"
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#include "llvm/OperandTraits.h"
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#include "llvm/ADT/ilist_node.h"
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#include "llvm/ADT/Twine.h"
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template<typename ValueSubClass, typename ItemParentClass>
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class SymbolTableListTraits;
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class GlobalVariable : public GlobalValue, public ilist_node<GlobalVariable> {
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friend class SymbolTableListTraits<GlobalVariable, Module>;
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void *operator new(size_t, unsigned); // Do not implement
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void operator=(const GlobalVariable &); // Do not implement
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GlobalVariable(const GlobalVariable &); // Do not implement
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void setParent(Module *parent);
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bool isConstantGlobal : 1; // Is this a global constant?
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bool isThreadLocalSymbol : 1; // Is this symbol "Thread Local"?
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// allocate space for exactly one operand
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void *operator new(size_t s) {
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return User::operator new(s, 1);
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/// GlobalVariable ctor - If a parent module is specified, the global is
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/// automatically inserted into the end of the specified modules global list.
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GlobalVariable(const Type *Ty, bool isConstant, LinkageTypes Linkage,
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Constant *Initializer = 0, const Twine &Name = "",
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bool ThreadLocal = false, unsigned AddressSpace = 0);
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/// GlobalVariable ctor - This creates a global and inserts it before the
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/// specified other global.
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GlobalVariable(Module &M, const Type *Ty, bool isConstant,
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LinkageTypes Linkage, Constant *Initializer,
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GlobalVariable *InsertBefore = 0, bool ThreadLocal = false,
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unsigned AddressSpace = 0);
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NumOperands = 1; // FIXME: needed by operator delete
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/// Provide fast operand accessors
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DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
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/// isDeclaration - Is this global variable lacking an initializer? If so,
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/// the global variable is defined in some other translation unit, and is thus
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/// only a declaration here.
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virtual bool isDeclaration() const { return getNumOperands() == 0; }
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/// hasInitializer - Unless a global variable isExternal(), it has an
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/// initializer. The initializer for the global variable/constant is held by
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/// Initializer if an initializer is specified.
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inline bool hasInitializer() const { return !isDeclaration(); }
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/// hasDefinitiveInitializer - Whether the global variable has an initializer,
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/// and this is the initializer that will be used in the final executable.
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inline bool hasDefinitiveInitializer() const {
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return hasInitializer() &&
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// The initializer of a global variable with weak linkage may change at
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/// getInitializer - Return the initializer for this global variable. It is
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/// illegal to call this method if the global is external, because we cannot
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/// tell what the value is initialized to!
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inline /*const FIXME*/ Constant *getInitializer() const {
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assert(hasInitializer() && "GV doesn't have initializer!");
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return static_cast<Constant*>(Op<0>().get());
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inline Constant *getInitializer() {
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assert(hasInitializer() && "GV doesn't have initializer!");
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return static_cast<Constant*>(Op<0>().get());
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/// setInitializer - Sets the initializer for this global variable, removing
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/// any existing initializer if InitVal==NULL. If this GV has type T*, the
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/// initializer must have type T.
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void setInitializer(Constant *InitVal);
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/// If the value is a global constant, its value is immutable throughout the
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/// runtime execution of the program. Assigning a value into the constant
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/// leads to undefined behavior.
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bool isConstant() const { return isConstantGlobal; }
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void setConstant(bool Val) { isConstantGlobal = Val; }
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/// If the value is "Thread Local", its value isn't shared by the threads.
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bool isThreadLocal() const { return isThreadLocalSymbol; }
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void setThreadLocal(bool Val) { isThreadLocalSymbol = Val; }
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/// copyAttributesFrom - copy all additional attributes (those not needed to
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/// create a GlobalVariable) from the GlobalVariable Src to this one.
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void copyAttributesFrom(const GlobalValue *Src);
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/// removeFromParent - This method unlinks 'this' from the containing module,
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/// but does not delete it.
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virtual void removeFromParent();
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/// eraseFromParent - This method unlinks 'this' from the containing module
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virtual void eraseFromParent();
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/// Override Constant's implementation of this method so we can
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/// replace constant initializers.
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virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
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// Methods for support type inquiry through isa, cast, and dyn_cast:
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static inline bool classof(const GlobalVariable *) { return true; }
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static inline bool classof(const Value *V) {
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return V->getValueID() == Value::GlobalVariableVal;
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struct OperandTraits<GlobalVariable> : public OptionalOperandTraits<> {
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DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalVariable, Value)
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} // End llvm namespace