GlobalAlias.h revision d68a07650cdb2e18f18f362ba533459aa10e01b6 
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
22namespace llvm {
23
24class Module;
25class Constant;
26template<typename ValueSubClass, typename ItemParentClass>
27  class SymbolTableListTraits;
28
29class 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
36public:
37  // allocate space for exactly one operand
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(const Type *Ty, LinkageTypes Linkage, const std::string &Name = "",
44              Constant* Aliasee = 0, Module *Parent = 0);
45
46  /// Provide fast operand accessors
47  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
48
49  /// isDeclaration - Is this global variable lacking an initializer?  If so,
50  /// the global variable is defined in some other translation unit, and is thus
51  /// only a declaration here.
52  virtual bool isDeclaration() const;
53
54  /// removeFromParent - This method unlinks 'this' from the containing module,
55  /// but does not delete it.
56  ///
57  virtual void removeFromParent();
58
59  /// eraseFromParent - This method unlinks 'this' from the containing module
60  /// and deletes it.
61  ///
62  virtual void eraseFromParent();
63
64  /// set/getAliasee - These methods retrive and set alias target.
65  void setAliasee(Constant* GV);
66  const Constant* getAliasee() const {
67    return cast_or_null<Constant>(getOperand(0));
68  }
69  Constant* getAliasee() {
70    return cast_or_null<Constant>(getOperand(0));
71  }
72  /// getAliasedGlobal() - Aliasee can be either global or bitcast of
73  /// global. This method retrives the global for both aliasee flavours.
74  const GlobalValue* getAliasedGlobal() const;
75
76  /// resolveAliasedGlobal() - This method tries to ultimately resolve the alias
77  /// by going through the aliasing chain and trying to find the very last
78  /// global. Returns NULL if a cycle was found. If stopOnWeak is false, then
79  /// the whole chain aliasing chain is traversed, otherwise - only strong
80  /// aliases.
81  const GlobalValue* resolveAliasedGlobal(bool stopOnWeak = true) const;
82
83  // Methods for support type inquiry through isa, cast, and dyn_cast:
84  static inline bool classof(const GlobalAlias *) { return true; }
85  static inline bool classof(const Value *V) {
86    return V->getValueID() == Value::GlobalAliasVal;
87  }
88};
89
90template <>
91struct OperandTraits<GlobalAlias> : FixedNumOperandTraits<1> {
92};
93
94DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalAlias, Value)
95
96} // End llvm namespace
97
98#endif
99