-//===-- llvm/Global.h - Class to represent a global variable -----*- C++ -*--=//
+//===-- llvm/GlobalVariable.h - GlobalVariable class ------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file 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 in the VM.
+// 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.
+// allocated by either the VM, or by the linker in a static compiler. A global
+// variable may have an initial value, which is copied into the executables .data
+// area. Global Constants are required to have initializers.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_GLOBAL_VARIABLE_H
#define LLVM_GLOBAL_VARIABLE_H
-#include "llvm/Value.h"
+#include "llvm/GlobalValue.h"
+#include "llvm/OperandTraits.h"
+#include "llvm/ADT/ilist_node.h"
+#include "llvm/ADT/Twine.h"
+
+namespace llvm {
+
class Module;
+class Constant;
+template<typename ValueSubClass, typename ItemParentClass>
+ class SymbolTableListTraits;
-class GlobalVariable : public Value {
- Module *Parent; // The module that contains this method
+class GlobalVariable : public GlobalValue, public ilist_node<GlobalVariable> {
+ friend class SymbolTableListTraits<GlobalVariable, Module>;
+ void *operator new(size_t, unsigned); // Do not implement
+ void operator=(const GlobalVariable &); // Do not implement
+ GlobalVariable(const GlobalVariable &); // Do not implement
- friend class ValueHolder<GlobalVariable, Module, Module>;
- void setParent(Module *parent) { Parent = parent; }
+ void setParent(Module *parent);
+
+ bool isConstantGlobal : 1; // Is this a global constant?
+ bool isThreadLocalSymbol : 1; // Is this symbol "Thread Local"?
public:
- GlobalVariable(const Type *Ty, const string &Name = "");
- ~GlobalVariable() {}
+ // allocate space for exactly one operand
+ void *operator new(size_t s) {
+ return User::operator new(s, 1);
+ }
+ /// GlobalVariable ctor - If a parent module is specified, the global is
+ /// automatically inserted into the end of the specified modules global list.
+ GlobalVariable(Type *Ty, bool isConstant, LinkageTypes Linkage,
+ Constant *Initializer = 0, const Twine &Name = "",
+ bool ThreadLocal = false, unsigned AddressSpace = 0);
+ /// GlobalVariable ctor - This creates a global and inserts it before the
+ /// specified other global.
+ GlobalVariable(Module &M, Type *Ty, bool isConstant,
+ LinkageTypes Linkage, Constant *Initializer,
+ const Twine &Name,
+ GlobalVariable *InsertBefore = 0, bool ThreadLocal = false,
+ unsigned AddressSpace = 0);
+
+ ~GlobalVariable() {
+ NumOperands = 1; // FIXME: needed by operator delete
+ }
+
+ /// Provide fast operand accessors
+ DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
+
+ /// 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 !isDeclaration(); }
+
+ /// hasDefinitiveInitializer - Whether the global variable has an initializer,
+ /// and any other instances of the global (this can happen due to weak
+ /// linkage) are guaranteed to have the same initializer.
+ ///
+ /// Note that if you want to transform a global, you must use
+ /// hasUniqueInitializer() instead, because of the *_odr linkage type.
+ ///
+ /// Example:
+ ///
+ /// @a = global SomeType* null - Initializer is both definitive and unique.
+ ///
+ /// @b = global weak SomeType* null - Initializer is neither definitive nor
+ /// unique.
+ ///
+ /// @c = global weak_odr SomeType* null - Initializer is definitive, but not
+ /// unique.
+ inline bool hasDefinitiveInitializer() const {
+ return hasInitializer() &&
+ // The initializer of a global variable with weak linkage may change at
+ // link time.
+ !mayBeOverridden();
+ }
- // Specialize setName to handle symbol table majik...
- virtual void setName(const string &name, SymbolTable *ST = 0);
+ /// hasUniqueInitializer - Whether the global variable has an initializer, and
+ /// any changes made to the initializer will turn up in the final executable.
+ inline bool hasUniqueInitializer() const {
+ return hasInitializer() &&
+ // It's not safe to modify initializers of global variables with weak
+ // linkage, because the linker might choose to discard the initializer and
+ // use the initializer from another instance of the global variable
+ // instead. It is wrong to modify the initializer of a global variable
+ // with *_odr linkage because then different instances of the global may
+ // have different initializers, breaking the One Definition Rule.
+ !isWeakForLinker();
+ }
- inline Module *getParent() { return Parent; }
- inline const Module *getParent() const { return Parent; }
+ /// 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 const Constant *getInitializer() const {
+ assert(hasInitializer() && "GV doesn't have initializer!");
+ return static_cast<Constant*>(Op<0>().get());
+ }
+ inline Constant *getInitializer() {
+ assert(hasInitializer() && "GV doesn't have initializer!");
+ return static_cast<Constant*>(Op<0>().get());
+ }
+ /// setInitializer - Sets the initializer for this global variable, removing
+ /// any existing initializer if InitVal==NULL. If this GV has type T*, the
+ /// initializer must have type T.
+ void setInitializer(Constant *InitVal);
+
+ /// 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 Val) { isConstantGlobal = Val; }
+
+ /// If the value is "Thread Local", its value isn't shared by the threads.
+ bool isThreadLocal() const { return isThreadLocalSymbol; }
+ void setThreadLocal(bool Val) { isThreadLocalSymbol = Val; }
+
+ /// copyAttributesFrom - copy all additional attributes (those not needed to
+ /// create a GlobalVariable) from the GlobalVariable Src to this one.
+ void copyAttributesFrom(const GlobalValue *Src);
+
+ /// removeFromParent - This method unlinks 'this' from the containing module,
+ /// but does not delete it.
+ ///
+ virtual void removeFromParent();
+
+ /// eraseFromParent - This method unlinks 'this' from the containing module
+ /// and deletes it.
+ ///
+ virtual void eraseFromParent();
+
+ /// Override Constant's implementation of this method so we can
+ /// replace constant initializers.
+ virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
+
+ // 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->getValueID() == Value::GlobalVariableVal;
+ }
+};
+
+template <>
+struct OperandTraits<GlobalVariable> :
+ public OptionalOperandTraits<GlobalVariable> {
};
+DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalVariable, Value)
+
+} // End llvm namespace
+
#endif
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