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llvm-mirror/include/llvm/GlobalValue.h
2011-07-18 04:54:35 +00:00

293 lines
12 KiB
C++

//===-- 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
AvailableExternallyLinkage, ///< Available for inspection, not emission.
LinkOnceAnyLinkage, ///< Keep one copy of function when linking (inline)
LinkOnceODRLinkage, ///< Same, but only replaced by something equivalent.
WeakAnyLinkage, ///< Keep one copy of named function when linking (weak)
WeakODRLinkage, ///< Same, but only replaced by something equivalent.
AppendingLinkage, ///< Special purpose, only applies to global arrays
InternalLinkage, ///< Rename collisions when linking (static functions).
PrivateLinkage, ///< Like Internal, but omit from symbol table.
LinkerPrivateLinkage, ///< Like Private, but linker removes.
LinkerPrivateWeakLinkage, ///< Like LinkerPrivate, but weak.
LinkerPrivateWeakDefAutoLinkage, ///< Like LinkerPrivateWeak, but possibly
/// hidden.
DLLImportLinkage, ///< Function to be imported from DLL
DLLExportLinkage, ///< Function to be accessible from DLL.
ExternalWeakLinkage,///< ExternalWeak linkage description.
CommonLinkage ///< Tentative definitions.
};
/// @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(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps,
LinkageTypes linkage, const Twine &Name)
: Constant(ty, vty, Ops, NumOps), Parent(0),
Linkage(linkage), Visibility(DefaultVisibility), Alignment(0),
UnnamedAddr(0) {
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
unsigned UnnamedAddr : 1; // This value's address is not significant
std::string Section; // Section to emit this into, empty mean default
public:
~GlobalValue() {
removeDeadConstantUsers(); // remove any dead constants using this.
}
unsigned getAlignment() const {
return (1u << Alignment) >> 1;
}
void setAlignment(unsigned Align);
bool hasUnnamedAddr() const { return UnnamedAddr; }
void setUnnamedAddr(bool Val) { UnnamedAddr = Val; }
VisibilityTypes getVisibility() const { return VisibilityTypes(Visibility); }
bool hasDefaultVisibility() const { return Visibility == DefaultVisibility; }
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(StringRef S) { Section = S; }
/// If the usage is empty (except transitively dead constants), then this
/// global value 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 PointerType *getType() const {
return reinterpret_cast<PointerType*>(User::getType());
}
static LinkageTypes getLinkOnceLinkage(bool ODR) {
return ODR ? LinkOnceODRLinkage : LinkOnceAnyLinkage;
}
static LinkageTypes getWeakLinkage(bool ODR) {
return ODR ? WeakODRLinkage : WeakAnyLinkage;
}
static bool isExternalLinkage(LinkageTypes Linkage) {
return Linkage == ExternalLinkage;
}
static bool isAvailableExternallyLinkage(LinkageTypes Linkage) {
return Linkage == AvailableExternallyLinkage;
}
static bool isLinkOnceLinkage(LinkageTypes Linkage) {
return Linkage == LinkOnceAnyLinkage || Linkage == LinkOnceODRLinkage;
}
static bool isWeakLinkage(LinkageTypes Linkage) {
return Linkage == WeakAnyLinkage || Linkage == WeakODRLinkage;
}
static bool isAppendingLinkage(LinkageTypes Linkage) {
return Linkage == AppendingLinkage;
}
static bool isInternalLinkage(LinkageTypes Linkage) {
return Linkage == InternalLinkage;
}
static bool isPrivateLinkage(LinkageTypes Linkage) {
return Linkage == PrivateLinkage;
}
static bool isLinkerPrivateLinkage(LinkageTypes Linkage) {
return Linkage == LinkerPrivateLinkage;
}
static bool isLinkerPrivateWeakLinkage(LinkageTypes Linkage) {
return Linkage == LinkerPrivateWeakLinkage;
}
static bool isLinkerPrivateWeakDefAutoLinkage(LinkageTypes Linkage) {
return Linkage == LinkerPrivateWeakDefAutoLinkage;
}
static bool isLocalLinkage(LinkageTypes Linkage) {
return isInternalLinkage(Linkage) || isPrivateLinkage(Linkage) ||
isLinkerPrivateLinkage(Linkage) || isLinkerPrivateWeakLinkage(Linkage) ||
isLinkerPrivateWeakDefAutoLinkage(Linkage);
}
static bool isDLLImportLinkage(LinkageTypes Linkage) {
return Linkage == DLLImportLinkage;
}
static bool isDLLExportLinkage(LinkageTypes Linkage) {
return Linkage == DLLExportLinkage;
}
static bool isExternalWeakLinkage(LinkageTypes Linkage) {
return Linkage == ExternalWeakLinkage;
}
static bool isCommonLinkage(LinkageTypes Linkage) {
return Linkage == CommonLinkage;
}
/// mayBeOverridden - Whether the definition of this global may be replaced
/// by something non-equivalent at link time. For example, if a function has
/// weak linkage then the code defining it may be replaced by different code.
static bool mayBeOverridden(LinkageTypes Linkage) {
return Linkage == WeakAnyLinkage ||
Linkage == LinkOnceAnyLinkage ||
Linkage == CommonLinkage ||
Linkage == ExternalWeakLinkage ||
Linkage == LinkerPrivateWeakLinkage ||
Linkage == LinkerPrivateWeakDefAutoLinkage;
}
/// isWeakForLinker - Whether the definition of this global may be replaced at
/// link time. NB: Using this method outside of the code generators is almost
/// always a mistake: when working at the IR level use mayBeOverridden instead
/// as it knows about ODR semantics.
static bool isWeakForLinker(LinkageTypes Linkage) {
return Linkage == AvailableExternallyLinkage ||
Linkage == WeakAnyLinkage ||
Linkage == WeakODRLinkage ||
Linkage == LinkOnceAnyLinkage ||
Linkage == LinkOnceODRLinkage ||
Linkage == CommonLinkage ||
Linkage == ExternalWeakLinkage ||
Linkage == LinkerPrivateWeakLinkage ||
Linkage == LinkerPrivateWeakDefAutoLinkage;
}
bool hasExternalLinkage() const { return isExternalLinkage(Linkage); }
bool hasAvailableExternallyLinkage() const {
return isAvailableExternallyLinkage(Linkage);
}
bool hasLinkOnceLinkage() const {
return isLinkOnceLinkage(Linkage);
}
bool hasWeakLinkage() const {
return isWeakLinkage(Linkage);
}
bool hasAppendingLinkage() const { return isAppendingLinkage(Linkage); }
bool hasInternalLinkage() const { return isInternalLinkage(Linkage); }
bool hasPrivateLinkage() const { return isPrivateLinkage(Linkage); }
bool hasLinkerPrivateLinkage() const { return isLinkerPrivateLinkage(Linkage); }
bool hasLinkerPrivateWeakLinkage() const {
return isLinkerPrivateWeakLinkage(Linkage);
}
bool hasLinkerPrivateWeakDefAutoLinkage() const {
return isLinkerPrivateWeakDefAutoLinkage(Linkage);
}
bool hasLocalLinkage() const { return isLocalLinkage(Linkage); }
bool hasDLLImportLinkage() const { return isDLLImportLinkage(Linkage); }
bool hasDLLExportLinkage() const { return isDLLExportLinkage(Linkage); }
bool hasExternalWeakLinkage() const { return isExternalWeakLinkage(Linkage); }
bool hasCommonLinkage() const { return isCommonLinkage(Linkage); }
void setLinkage(LinkageTypes LT) { Linkage = LT; }
LinkageTypes getLinkage() const { return Linkage; }
bool mayBeOverridden() const { return mayBeOverridden(Linkage); }
bool isWeakForLinker() const { return isWeakForLinker(Linkage); }
/// copyAttributesFrom - copy all additional attributes (those not needed to
/// create a GlobalValue) from the GlobalValue Src to this one.
virtual void copyAttributesFrom(const GlobalValue *Src);
/// @name Materialization
/// Materialization is used to construct functions only as they're needed. This
/// is useful to reduce memory usage in LLVM or parsing work done by the
/// BitcodeReader to load the Module.
/// @{
/// isMaterializable - If this function's Module is being lazily streamed in
/// functions from disk or some other source, this method can be used to check
/// to see if the function has been read in yet or not.
bool isMaterializable() const;
/// isDematerializable - Returns true if this function was loaded from a
/// GVMaterializer that's still attached to its Module and that knows how to
/// dematerialize the function.
bool isDematerializable() const;
/// Materialize - make sure this GlobalValue is fully read. If the module is
/// corrupt, this returns true and fills in the optional string with
/// information about the problem. If successful, this returns false.
bool Materialize(std::string *ErrInfo = 0);
/// Dematerialize - If this GlobalValue is read in, and if the GVMaterializer
/// supports it, release the memory for the function, and set it up to be
/// materialized lazily. If !isDematerializable(), this method is a noop.
void Dematerialize();
/// @}
/// 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.
bool isDeclaration() const;
/// removeFromParent - This method unlinks 'this' from the containing module,
/// but does not delete it.
virtual void removeFromParent() = 0;
/// eraseFromParent - This method unlinks 'this' from the containing module
/// and deletes it.
virtual void eraseFromParent() = 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; }
// 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