//
// 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
+// variable may have an initial value, which is copied into the executables .data
// area. Global Constants are required to have initializers.
//
//===----------------------------------------------------------------------===//
#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;
-class PointerType;
template<typename ValueSubClass, typename ItemParentClass>
class SymbolTableListTraits;
}
/// 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, bool ThreadLocal = false,
- unsigned AddressSpace = 0);
+ 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(const Type *Ty, bool isConstant, LinkageTypes Linkage,
- Constant *Initializer, const std::string &Name,
- GlobalVariable *InsertBefore, bool ThreadLocal = false,
+ GlobalVariable(Module &M, Type *Ty, bool isConstant,
+ LinkageTypes Linkage, Constant *Initializer,
+ const Twine &Name,
+ GlobalVariable *InsertBefore = 0, bool ThreadLocal = false,
unsigned AddressSpace = 0);
~GlobalVariable() {
/// Provide fast operand accessors
DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
- /// isDeclaration - Is this global variable lacking an initializer? If so,
- /// the global variable is defined in some other translation unit, and is thus
- /// only a declaration here.
- virtual bool isDeclaration() 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 !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();
+ }
+
+ /// 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();
+ }
+
/// 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 FIXME*/ Constant *getInitializer() const {
+ inline const Constant *getInitializer() const {
assert(hasInitializer() && "GV doesn't have initializer!");
return static_cast<Constant*>(Op<0>().get());
}
assert(hasInitializer() && "GV doesn't have initializer!");
return static_cast<Constant*>(Op<0>().get());
}
- inline void setInitializer(Constant *CPV) {
- if (CPV == 0) {
- if (hasInitializer()) {
- Op<0>().set(0);
- NumOperands = 0;
- }
- } else {
- if (!hasInitializer())
- NumOperands = 1;
- Op<0>().set(CPV);
- }
- }
+ /// 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
/// removeFromParent - This method unlinks 'this' from the containing module,
/// but does not delete it.
///
- void removeFromParent();
+ virtual void removeFromParent();
/// eraseFromParent - This method unlinks 'this' from the containing module
/// and deletes it.
///
- void eraseFromParent();
+ 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);
- virtual void print(std::ostream &OS) const;
- void print(std::ostream *OS) const { if (OS) print(*OS); }
-
// 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) {
};
template <>
-struct OperandTraits<GlobalVariable> : OptionalOperandTraits<> {
+struct OperandTraits<GlobalVariable> :
+ public OptionalOperandTraits<GlobalVariable> {
};
DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalVariable, Value)
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