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      1 //===-------- llvm/GlobalAlias.h - GlobalAlias class ------------*- C++ -*-===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 //
      9 // This file contains the declaration of the GlobalAlias class, which
     10 // represents a single function or variable alias in the IR.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_IR_GLOBALALIAS_H
     15 #define LLVM_IR_GLOBALALIAS_H
     16 
     17 #include "llvm/ADT/ilist_node.h"
     18 #include "llvm/IR/GlobalIndirectSymbol.h"
     19 #include "llvm/IR/Value.h"
     20 
     21 namespace llvm {
     22 
     23 class Twine;
     24 class Module;
     25 template <typename ValueSubClass> class SymbolTableListTraits;
     26 
     27 class GlobalAlias : public GlobalIndirectSymbol,
     28                     public ilist_node<GlobalAlias> {
     29   friend class SymbolTableListTraits<GlobalAlias>;
     30 
     31   GlobalAlias(Type *Ty, unsigned AddressSpace, LinkageTypes Linkage,
     32               const Twine &Name, Constant *Aliasee, Module *Parent);
     33 
     34 public:
     35   GlobalAlias(const GlobalAlias &) = delete;
     36   GlobalAlias &operator=(const GlobalAlias &) = delete;
     37 
     38   /// If a parent module is specified, the alias is automatically inserted into
     39   /// the end of the specified module's alias list.
     40   static GlobalAlias *create(Type *Ty, unsigned AddressSpace,
     41                              LinkageTypes Linkage, const Twine &Name,
     42                              Constant *Aliasee, Module *Parent);
     43 
     44   // Without the Aliasee.
     45   static GlobalAlias *create(Type *Ty, unsigned AddressSpace,
     46                              LinkageTypes Linkage, const Twine &Name,
     47                              Module *Parent);
     48 
     49   // The module is taken from the Aliasee.
     50   static GlobalAlias *create(Type *Ty, unsigned AddressSpace,
     51                              LinkageTypes Linkage, const Twine &Name,
     52                              GlobalValue *Aliasee);
     53 
     54   // Type, Parent and AddressSpace taken from the Aliasee.
     55   static GlobalAlias *create(LinkageTypes Linkage, const Twine &Name,
     56                              GlobalValue *Aliasee);
     57 
     58   // Linkage, Type, Parent and AddressSpace taken from the Aliasee.
     59   static GlobalAlias *create(const Twine &Name, GlobalValue *Aliasee);
     60 
     61   /// removeFromParent - This method unlinks 'this' from the containing module,
     62   /// but does not delete it.
     63   ///
     64   void removeFromParent();
     65 
     66   /// eraseFromParent - This method unlinks 'this' from the containing module
     67   /// and deletes it.
     68   ///
     69   void eraseFromParent();
     70 
     71   /// These methods retrieve and set alias target.
     72   void setAliasee(Constant *Aliasee);
     73   const Constant *getAliasee() const {
     74     return getIndirectSymbol();
     75   }
     76   Constant *getAliasee() {
     77     return getIndirectSymbol();
     78   }
     79 
     80   static bool isValidLinkage(LinkageTypes L) {
     81     return isExternalLinkage(L) || isLocalLinkage(L) ||
     82       isWeakLinkage(L) || isLinkOnceLinkage(L);
     83   }
     84 
     85   // Methods for support type inquiry through isa, cast, and dyn_cast:
     86   static bool classof(const Value *V) {
     87     return V->getValueID() == Value::GlobalAliasVal;
     88   }
     89 };
     90 
     91 } // end namespace llvm
     92 
     93 #endif // LLVM_IR_GLOBALALIAS_H
     94