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/GlobalValue.h"
19#include "llvm/IR/OperandTraits.h"
20#include "llvm/IR/Value.h"
21
22namespace llvm {
23
24class Twine;
25class Module;
26template <typename ValueSubClass, typename... Args> class SymbolTableListTraits;
27
28class GlobalAlias : public GlobalValue, 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
34public:
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  // allocate space for exactly one operand
62  void *operator new(size_t S) { return User::operator new(S, 1); }
63  void operator delete(void *Ptr) { User::operator delete(Ptr); }
64
65  /// Provide fast operand accessors
66  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Constant);
67
68  void copyAttributesFrom(const GlobalAlias *Src) {
69    GlobalValue::copyAttributesFrom(Src);
70  }
71
72  /// removeFromParent - This method unlinks 'this' from the containing module,
73  /// but does not delete it.
74  ///
75  void removeFromParent();
76
77  /// eraseFromParent - This method unlinks 'this' from the containing module
78  /// and deletes it.
79  ///
80  void eraseFromParent();
81
82  /// These methods retrieve and set alias target.
83  void setAliasee(Constant *Aliasee);
84  const Constant *getAliasee() const {
85    return static_cast<Constant *>(Op<0>().get());
86  }
87  Constant *getAliasee() { return static_cast<Constant *>(Op<0>().get()); }
88
89  const GlobalObject *getAliaseeObject() const;
90  GlobalObject *getAliaseeObject() {
91    return const_cast<GlobalObject *>(
92        static_cast<const GlobalAlias *>(this)->getAliaseeObject());
93  }
94
95  static bool isValidLinkage(LinkageTypes L) {
96    return isExternalLinkage(L) || isLocalLinkage(L) || isWeakLinkage(L) ||
97           isLinkOnceLinkage(L) || isAvailableExternallyLinkage(L);
98  }
99
100  // Methods for support type inquiry through isa, cast, and dyn_cast:
101  static bool classof(const Value *V) {
102    return V->getValueID() == Value::GlobalAliasVal;
103  }
104};
105
106template <>
107struct OperandTraits<GlobalAlias>
108    : public FixedNumOperandTraits<GlobalAlias, 1> {};
109
110DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalAlias, Constant)
111
112} // end namespace llvm
113
114#endif // LLVM_IR_GLOBALALIAS_H
115