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216 lines
9.0 KiB
C++
216 lines
9.0 KiB
C++
//===-- llvm/GlobalValue.h - Class to represent a global value --*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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//
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// This file is a common base class of all globally definable objects. As such,
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// it is subclassed by GlobalVariable, GlobalAlias and by Function. This is
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// used because you can do certain things with these global objects that you
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// can't do to anything else. For example, use the address of one as a
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// constant.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_GLOBALVALUE_H
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#define LLVM_GLOBALVALUE_H
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#include "llvm/Constant.h"
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namespace llvm {
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class PointerType;
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class Module;
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class GlobalValue : public Constant {
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GlobalValue(const GlobalValue &); // do not implement
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public:
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/// @brief An enumeration for the kinds of linkage for global values.
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enum LinkageTypes {
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ExternalLinkage = 0,///< Externally visible function
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AvailableExternallyLinkage, ///< Available for inspection, not emission.
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LinkOnceAnyLinkage, ///< Keep one copy of function when linking (inline)
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LinkOnceODRLinkage, ///< Same, but only replaced by something equivalent.
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WeakAnyLinkage, ///< Keep one copy of named function when linking (weak)
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WeakODRLinkage, ///< Same, but only replaced by something equivalent.
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AppendingLinkage, ///< Special purpose, only applies to global arrays
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InternalLinkage, ///< Rename collisions when linking (static functions).
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PrivateLinkage, ///< Like Internal, but omit from symbol table.
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LinkerPrivateLinkage, ///< Like Private, but linker removes.
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DLLImportLinkage, ///< Function to be imported from DLL
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DLLExportLinkage, ///< Function to be accessible from DLL.
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ExternalWeakLinkage,///< ExternalWeak linkage description.
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GhostLinkage, ///< Stand-in functions for streaming fns from BC files.
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CommonLinkage ///< Tentative definitions.
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};
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/// @brief An enumeration for the kinds of visibility of global values.
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enum VisibilityTypes {
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DefaultVisibility = 0, ///< The GV is visible
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HiddenVisibility, ///< The GV is hidden
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ProtectedVisibility ///< The GV is protected
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};
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protected:
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GlobalValue(const Type *ty, ValueTy vty, Use *Ops, unsigned NumOps,
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LinkageTypes linkage, const Twine &Name = "")
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: Constant(ty, vty, Ops, NumOps), Parent(0),
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Linkage(linkage), Visibility(DefaultVisibility), Alignment(0) {
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setName(Name);
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}
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Module *Parent;
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// Note: VC++ treats enums as signed, so an extra bit is required to prevent
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// Linkage and Visibility from turning into negative values.
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LinkageTypes Linkage : 5; // The linkage of this global
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unsigned Visibility : 2; // The visibility style of this global
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unsigned Alignment : 16; // Alignment of this symbol, must be power of two
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std::string Section; // Section to emit this into, empty mean default
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public:
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~GlobalValue() {
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removeDeadConstantUsers(); // remove any dead constants using this.
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}
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unsigned getAlignment() const { return Alignment; }
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void setAlignment(unsigned Align) {
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assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
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Alignment = Align;
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}
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VisibilityTypes getVisibility() const { return VisibilityTypes(Visibility); }
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bool hasDefaultVisibility() const { return Visibility == DefaultVisibility; }
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bool hasHiddenVisibility() const { return Visibility == HiddenVisibility; }
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bool hasProtectedVisibility() const {
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return Visibility == ProtectedVisibility;
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}
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void setVisibility(VisibilityTypes V) { Visibility = V; }
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bool hasSection() const { return !Section.empty(); }
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const std::string &getSection() const { return Section; }
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void setSection(const StringRef &S) { Section = S; }
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/// If the usage is empty (except transitively dead constants), then this
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/// global value can can be safely deleted since the destructor will
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/// delete the dead constants as well.
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/// @brief Determine if the usage of this global value is empty except
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/// for transitively dead constants.
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bool use_empty_except_constants();
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/// getType - Global values are always pointers.
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inline const PointerType *getType() const {
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return reinterpret_cast<const PointerType*>(User::getType());
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}
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static LinkageTypes getLinkOnceLinkage(bool ODR) {
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return ODR ? LinkOnceODRLinkage : LinkOnceAnyLinkage;
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}
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static LinkageTypes getWeakLinkage(bool ODR) {
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return ODR ? WeakODRLinkage : WeakAnyLinkage;
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}
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bool hasExternalLinkage() const { return Linkage == ExternalLinkage; }
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bool hasAvailableExternallyLinkage() const {
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return Linkage == AvailableExternallyLinkage;
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}
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bool hasLinkOnceLinkage() const {
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return Linkage == LinkOnceAnyLinkage || Linkage == LinkOnceODRLinkage;
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}
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bool hasWeakLinkage() const {
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return Linkage == WeakAnyLinkage || Linkage == WeakODRLinkage;
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}
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bool hasAppendingLinkage() const { return Linkage == AppendingLinkage; }
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bool hasInternalLinkage() const { return Linkage == InternalLinkage; }
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bool hasPrivateLinkage() const { return Linkage == PrivateLinkage; }
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bool hasLinkerPrivateLinkage() const { return Linkage==LinkerPrivateLinkage; }
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bool hasLocalLinkage() const {
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return hasInternalLinkage() || hasPrivateLinkage() ||
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hasLinkerPrivateLinkage();
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}
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bool hasDLLImportLinkage() const { return Linkage == DLLImportLinkage; }
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bool hasDLLExportLinkage() const { return Linkage == DLLExportLinkage; }
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bool hasExternalWeakLinkage() const { return Linkage == ExternalWeakLinkage; }
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bool hasGhostLinkage() const { return Linkage == GhostLinkage; }
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bool hasCommonLinkage() const { return Linkage == CommonLinkage; }
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void setLinkage(LinkageTypes LT) { Linkage = LT; }
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LinkageTypes getLinkage() const { return Linkage; }
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/// mayBeOverridden - Whether the definition of this global may be replaced
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/// by something non-equivalent at link time. For example, if a function has
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/// weak linkage then the code defining it may be replaced by different code.
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bool mayBeOverridden() const {
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return (Linkage == WeakAnyLinkage ||
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Linkage == LinkOnceAnyLinkage ||
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Linkage == CommonLinkage ||
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Linkage == ExternalWeakLinkage);
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}
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/// isWeakForLinker - Whether the definition of this global may be replaced at
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/// link time.
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bool isWeakForLinker() const {
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return (Linkage == AvailableExternallyLinkage ||
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Linkage == WeakAnyLinkage ||
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Linkage == WeakODRLinkage ||
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Linkage == LinkOnceAnyLinkage ||
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Linkage == LinkOnceODRLinkage ||
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Linkage == CommonLinkage ||
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Linkage == ExternalWeakLinkage);
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}
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/// copyAttributesFrom - copy all additional attributes (those not needed to
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/// create a GlobalValue) from the GlobalValue Src to this one.
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virtual void copyAttributesFrom(const GlobalValue *Src);
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/// hasNotBeenReadFromBitcode - If a module provider is being used to lazily
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/// stream in functions from disk, this method can be used to check to see if
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/// the function has been read in yet or not. Unless you are working on the
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/// JIT or something else that streams stuff in lazily, you don't need to
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/// worry about this.
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bool hasNotBeenReadFromBitcode() const { return Linkage == GhostLinkage; }
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/// Override from Constant class. No GlobalValue's are null values so this
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/// always returns false.
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virtual bool isNullValue() const { return false; }
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/// Override from Constant class.
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virtual void destroyConstant();
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/// isDeclaration - Return true if the primary definition of this global
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/// value is outside of the current translation unit...
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virtual bool isDeclaration() const = 0;
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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() = 0;
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/// eraseFromParent - This method unlinks 'this' from the containing module
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/// and deletes it.
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virtual void eraseFromParent() = 0;
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/// getParent - Get the module that this global value is contained inside
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/// of...
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inline Module *getParent() { return Parent; }
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inline const Module *getParent() const { return Parent; }
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/// removeDeadConstantUsers - If there are any dead constant users dangling
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/// off of this global value, remove them. This method is useful for clients
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/// that want to check to see if a global is unused, but don't want to deal
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/// with potentially dead constants hanging off of the globals.
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void removeDeadConstantUsers() const;
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// Methods for support type inquiry through isa, cast, and dyn_cast:
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static inline bool classof(const GlobalValue *) { return true; }
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static inline bool classof(const Value *V) {
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return V->getValueID() == Value::FunctionVal ||
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V->getValueID() == Value::GlobalVariableVal ||
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V->getValueID() == Value::GlobalAliasVal;
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}
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};
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} // End llvm namespace
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#endif
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