1 //===-------- llvm/GlobalAlias.h - GlobalAlias class ------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains the declaration of the GlobalAlias class, which
11 // represents a single function or variable alias in the IR.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_GLOBAL_ALIAS_H
16 #define LLVM_GLOBAL_ALIAS_H
17 
18 #include "llvm/GlobalValue.h"
19 #include "llvm/OperandTraits.h"
20 #include "llvm/ADT/ilist_node.h"
21 #include "llvm/ADT/Twine.h"
22 
23 namespace llvm {
24 
25 class Module;
26 template<typename ValueSubClass, typename ItemParentClass>
27   class SymbolTableListTraits;
28 
29 class GlobalAlias : public GlobalValue, public ilist_node<GlobalAlias> {
30   friend class SymbolTableListTraits<GlobalAlias, Module>;
31   void operator=(const GlobalAlias &);     // Do not implement
32   GlobalAlias(const GlobalAlias &);     // Do not implement
33 
34   void setParent(Module *parent);
35 
36 public:
37   // allocate space for exactly one operand
new(size_t s)38   void *operator new(size_t s) {
39     return User::operator new(s, 1);
40   }
41   /// GlobalAlias ctor - If a parent module is specified, the alias is
42   /// automatically inserted into the end of the specified module's alias list.
43   GlobalAlias(Type *Ty, LinkageTypes Linkage, const Twine &Name = "",
44               Constant* Aliasee = 0, Module *Parent = 0);
45 
46   /// Provide fast operand accessors
47   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Constant);
48 
49   /// removeFromParent - This method unlinks 'this' from the containing module,
50   /// but does not delete it.
51   ///
52   virtual void removeFromParent();
53 
54   /// eraseFromParent - This method unlinks 'this' from the containing module
55   /// and deletes it.
56   ///
57   virtual void eraseFromParent();
58 
59   /// set/getAliasee - These methods retrive and set alias target.
60   void setAliasee(Constant *GV);
getAliasee()61   const Constant *getAliasee() const {
62     return getOperand(0);
63   }
getAliasee()64   Constant *getAliasee() {
65     return getOperand(0);
66   }
67   /// getAliasedGlobal() - Aliasee can be either global or bitcast of
68   /// global. This method retrives the global for both aliasee flavours.
69   const GlobalValue *getAliasedGlobal() const;
70 
71   /// resolveAliasedGlobal() - This method tries to ultimately resolve the alias
72   /// by going through the aliasing chain and trying to find the very last
73   /// global. Returns NULL if a cycle was found. If stopOnWeak is false, then
74   /// the whole chain aliasing chain is traversed, otherwise - only strong
75   /// aliases.
76   const GlobalValue *resolveAliasedGlobal(bool stopOnWeak = true) const;
77 
78   // Methods for support type inquiry through isa, cast, and dyn_cast:
classof(const GlobalAlias *)79   static inline bool classof(const GlobalAlias *) { return true; }
classof(const Value * V)80   static inline bool classof(const Value *V) {
81     return V->getValueID() == Value::GlobalAliasVal;
82   }
83 };
84 
85 template <>
86 struct OperandTraits<GlobalAlias> :
87   public FixedNumOperandTraits<GlobalAlias, 1> {
88 };
89 
90 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalAlias, Constant)
91 
92 } // End llvm namespace
93 
94 #endif
95