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the section or the visibility from one global value to another: copyAttributesFrom. This is particularly useful for duplicating functions: previously this was done by explicitly copying each attribute in turn at each place where a new function was created out of an old one, with the result that obscure attributes were regularly forgotten (like the collector or the section). Hopefully now everything is uniform and nothing is forgotten. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51567 91177308-0d34-0410-b5e6-96231b3b80d8
158 lines
6.7 KiB
C++
158 lines
6.7 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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LinkOnceLinkage, ///< Keep one copy of function when linking (inline)
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WeakLinkage, ///< Keep one copy of named function when linking (weak)
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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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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 std::string &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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if (!name.empty()) 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 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 std::string &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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bool hasExternalLinkage() const { return Linkage == ExternalLinkage; }
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bool hasLinkOnceLinkage() const { return Linkage == LinkOnceLinkage; }
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bool hasWeakLinkage() const { return Linkage == WeakLinkage; }
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bool hasCommonLinkage() const { return Linkage == CommonLinkage; }
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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 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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void setLinkage(LinkageTypes LT) { Linkage = LT; }
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LinkageTypes getLinkage() const { return Linkage; }
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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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/// 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();
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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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