aboutsummaryrefslogtreecommitdiffstats
path: root/include/llvm/GlobalValue.h
blob: 7f7f74b1e2da5e34b33c147c99871cfbb4fef11b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
//===-- llvm/GlobalValue.h - Class to represent a global value --*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a common base class of all globally definable objects.  As such,
// it is subclassed by GlobalVariable, GlobalAlias and by Function.  This is
// used because you can do certain things with these global objects that you
// can't do to anything else.  For example, use the address of one as a
// constant.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_GLOBALVALUE_H
#define LLVM_GLOBALVALUE_H

#include "llvm/Constant.h"

namespace llvm {

class PointerType;
class Module;

class GlobalValue : public Constant {
  GlobalValue(const GlobalValue &) LLVM_DELETED_FUNCTION;
public:
  /// @brief An enumeration for the kinds of linkage for global values.
  enum LinkageTypes {
    ExternalLinkage = 0,///< Externally visible function
    AvailableExternallyLinkage, ///< Available for inspection, not emission.
    LinkOnceAnyLinkage, ///< Keep one copy of function when linking (inline)
    LinkOnceODRLinkage, ///< Same, but only replaced by something equivalent.
    LinkOnceODRAutoHideLinkage, ///< Like LinkOnceODRLinkage but addr not taken.
    WeakAnyLinkage,     ///< Keep one copy of named function when linking (weak)
    WeakODRLinkage,     ///< Same, but only replaced by something equivalent.
    AppendingLinkage,   ///< Special purpose, only applies to global arrays
    InternalLinkage,    ///< Rename collisions when linking (static functions).
    PrivateLinkage,     ///< Like Internal, but omit from symbol table.
    LinkerPrivateLinkage, ///< Like Private, but linker removes.
    LinkerPrivateWeakLinkage, ///< Like LinkerPrivate, but weak.
    DLLImportLinkage,   ///< Function to be imported from DLL
    DLLExportLinkage,   ///< Function to be accessible from DLL.
    ExternalWeakLinkage,///< ExternalWeak linkage description.
    CommonLinkage       ///< Tentative definitions.
  };

  /// @brief An enumeration for the kinds of visibility of global values.
  enum VisibilityTypes {
    DefaultVisibility = 0,  ///< The GV is visible
    HiddenVisibility,       ///< The GV is hidden
    ProtectedVisibility     ///< The GV is protected
  };

protected:
  GlobalValue(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps,
              LinkageTypes linkage, const Twine &Name)
    : Constant(ty, vty, Ops, NumOps), Linkage(linkage),
      Visibility(DefaultVisibility), Alignment(0), UnnamedAddr(0), Parent(0) {
    setName(Name);
  }

  // Note: VC++ treats enums as signed, so an extra bit is required to prevent
  // Linkage and Visibility from turning into negative values.
  LinkageTypes Linkage : 5;   // The linkage of this global
  unsigned Visibility : 2;    // The visibility style of this global
  unsigned Alignment : 16;    // Alignment of this symbol, must be power of two
  unsigned UnnamedAddr : 1;   // This value's address is not significant
  Module *Parent;             // The containing module.
  std::string Section;        // Section to emit this into, empty mean default
public:
  ~GlobalValue() {
    removeDeadConstantUsers();   // remove any dead constants using this.
  }

  unsigned getAlignment() const {
    return (1u << Alignment) >> 1;
  }
  void setAlignment(unsigned Align);

  bool hasUnnamedAddr() const { return UnnamedAddr; }
  void setUnnamedAddr(bool Val) { UnnamedAddr = Val; }

  VisibilityTypes getVisibility() const { return VisibilityTypes(Visibility); }
  bool hasDefaultVisibility() const { return Visibility == DefaultVisibility; }
  bool hasHiddenVisibility() const { return Visibility == HiddenVisibility; }
  bool hasProtectedVisibility() const {
    return Visibility == ProtectedVisibility;
  }
  void setVisibility(VisibilityTypes V) { Visibility = V; }
  
  bool hasSection() const { return !Section.empty(); }
  const std::string &getSection() const { return Section; }
  void setSection(StringRef S) { Section = S; }
  
  /// If the usage is empty (except transitively dead constants), then this
  /// global value can be safely deleted since the destructor will
  /// delete the dead constants as well.
  /// @brief Determine if the usage of this global value is empty except
  /// for transitively dead constants.
  bool use_empty_except_constants();

  /// getType - Global values are always pointers.
  inline PointerType *getType() const {
    return reinterpret_cast<PointerType*>(User::getType());
  }

  static LinkageTypes getLinkOnceLinkage(bool ODR) {
    return ODR ? LinkOnceODRLinkage : LinkOnceAnyLinkage;
  }
  static LinkageTypes getWeakLinkage(bool ODR) {
    return ODR ? WeakODRLinkage : WeakAnyLinkage;
  }

  static bool isExternalLinkage(LinkageTypes Linkage) {
    return Linkage == ExternalLinkage;
  }
  static bool isAvailableExternallyLinkage(LinkageTypes Linkage) {
    return Linkage == AvailableExternallyLinkage;
  }
  static bool isLinkOnceLinkage(LinkageTypes Linkage) {
    return Linkage == LinkOnceAnyLinkage ||
           Linkage == LinkOnceODRLinkage ||
           Linkage == LinkOnceODRAutoHideLinkage;
  }
  static bool isLinkOnceODRAutoHideLinkage(LinkageTypes Linkage) {
    return Linkage == LinkOnceODRAutoHideLinkage;
  }
  static bool isWeakLinkage(LinkageTypes Linkage) {
    return Linkage == WeakAnyLinkage || Linkage == WeakODRLinkage;
  }
  static bool isAppendingLinkage(LinkageTypes Linkage) {
    return Linkage == AppendingLinkage;
  }
  static bool isInternalLinkage(LinkageTypes Linkage) {
    return Linkage == InternalLinkage;
  }
  static bool isPrivateLinkage(LinkageTypes Linkage) {
    return Linkage == PrivateLinkage;
  }
  static bool isLinkerPrivateLinkage(LinkageTypes Linkage) {
    return Linkage == LinkerPrivateLinkage;
  }
  static bool isLinkerPrivateWeakLinkage(LinkageTypes Linkage) {
    return Linkage == LinkerPrivateWeakLinkage;
  }
  static bool isLocalLinkage(LinkageTypes Linkage) {
    return isInternalLinkage(Linkage) || isPrivateLinkage(Linkage) ||
      isLinkerPrivateLinkage(Linkage) || isLinkerPrivateWeakLinkage(Linkage);
  }
  static bool isDLLImportLinkage(LinkageTypes Linkage) {
    return Linkage == DLLImportLinkage;
  }
  static bool isDLLExportLinkage(LinkageTypes Linkage) {
    return Linkage == DLLExportLinkage;
  }
  static bool isExternalWeakLinkage(LinkageTypes Linkage) {
    return Linkage == ExternalWeakLinkage;
  }
  static bool isCommonLinkage(LinkageTypes Linkage) {
    return Linkage == CommonLinkage;
  }

  /// isDiscardableIfUnused - Whether the definition of this global may be
  /// discarded if it is not used in its compilation unit.
  static bool isDiscardableIfUnused(LinkageTypes Linkage) {
    return isLinkOnceLinkage(Linkage) || isLocalLinkage(Linkage);
  }

  /// mayBeOverridden - Whether the definition of this global may be replaced
  /// by something non-equivalent at link time.  For example, if a function has
  /// weak linkage then the code defining it may be replaced by different code.
  static bool mayBeOverridden(LinkageTypes Linkage) {
    return Linkage == WeakAnyLinkage ||
           Linkage == LinkOnceAnyLinkage ||
           Linkage == CommonLinkage ||
           Linkage == ExternalWeakLinkage ||
           Linkage == LinkerPrivateWeakLinkage;
  }

  /// isWeakForLinker - Whether the definition of this global may be replaced at
  /// link time.  NB: Using this method outside of the code generators is almost
  /// always a mistake: when working at the IR level use mayBeOverridden instead
  /// as it knows about ODR semantics.
  static bool isWeakForLinker(LinkageTypes Linkage)  {
    return Linkage == AvailableExternallyLinkage ||
           Linkage == WeakAnyLinkage ||
           Linkage == WeakODRLinkage ||
           Linkage == LinkOnceAnyLinkage ||
           Linkage == LinkOnceODRLinkage ||
           Linkage == LinkOnceODRAutoHideLinkage ||
           Linkage == CommonLinkage ||
           Linkage == ExternalWeakLinkage ||
           Linkage == LinkerPrivateWeakLinkage;
  }

  bool hasExternalLinkage() const { return isExternalLinkage(Linkage); }
  bool hasAvailableExternallyLinkage() const {
    return isAvailableExternallyLinkage(Linkage);
  }
  bool hasLinkOnceLinkage() const {
    return isLinkOnceLinkage(Linkage);
  }
  bool hasLinkOnceODRAutoHideLinkage() const {
    return isLinkOnceODRAutoHideLinkage(Linkage);
  }
  bool hasWeakLinkage() const {
    return isWeakLinkage(Linkage);
  }
  bool hasAppendingLinkage() const { return isAppendingLinkage(Linkage); }
  bool hasInternalLinkage() const { return isInternalLinkage(Linkage); }
  bool hasPrivateLinkage() const { return isPrivateLinkage(Linkage); }
  bool hasLinkerPrivateLinkage() const { return isLinkerPrivateLinkage(Linkage); }
  bool hasLinkerPrivateWeakLinkage() const {
    return isLinkerPrivateWeakLinkage(Linkage);
  }
  bool hasLocalLinkage() const { return isLocalLinkage(Linkage); }
  bool hasDLLImportLinkage() const { return isDLLImportLinkage(Linkage); }
  bool hasDLLExportLinkage() const { return isDLLExportLinkage(Linkage); }
  bool hasExternalWeakLinkage() const { return isExternalWeakLinkage(Linkage); }
  bool hasCommonLinkage() const { return isCommonLinkage(Linkage); }

  void setLinkage(LinkageTypes LT) { Linkage = LT; }
  LinkageTypes getLinkage() const { return Linkage; }

  bool isDiscardableIfUnused() const {
    return isDiscardableIfUnused(Linkage);
  }

  bool mayBeOverridden() const { return mayBeOverridden(Linkage); }

  bool isWeakForLinker() const { return isWeakForLinker(Linkage); }

  /// copyAttributesFrom - copy all additional attributes (those not needed to
  /// create a GlobalValue) from the GlobalValue Src to this one.
  virtual void copyAttributesFrom(const GlobalValue *Src);

/// @name Materialization
/// Materialization is used to construct functions only as they're needed. This
/// is useful to reduce memory usage in LLVM or parsing work done by the
/// BitcodeReader to load the Module.
/// @{

  /// isMaterializable - If this function's Module is being lazily streamed in
  /// functions from disk or some other source, this method can be used to check
  /// to see if the function has been read in yet or not.
  bool isMaterializable() const;

  /// isDematerializable - Returns true if this function was loaded from a
  /// GVMaterializer that's still attached to its Module and that knows how to
  /// dematerialize the function.
  bool isDematerializable() const;

  /// Materialize - make sure this GlobalValue is fully read.  If the module is
  /// corrupt, this returns true and fills in the optional string with
  /// information about the problem.  If successful, this returns false.
  bool Materialize(std::string *ErrInfo = 0);

  /// Dematerialize - If this GlobalValue is read in, and if the GVMaterializer
  /// supports it, release the memory for the function, and set it up to be
  /// materialized lazily.  If !isDematerializable(), this method is a noop.
  void Dematerialize();

/// @}

  /// Override from Constant class.
  virtual void destroyConstant();

  /// isDeclaration - Return true if the primary definition of this global 
  /// value is outside of the current translation unit.
  bool isDeclaration() const;

  /// removeFromParent - This method unlinks 'this' from the containing module,
  /// but does not delete it.
  virtual void removeFromParent() = 0;

  /// eraseFromParent - This method unlinks 'this' from the containing module
  /// and deletes it.
  virtual void eraseFromParent() = 0;

  /// getParent - Get the module that this global value is contained inside
  /// of...
  inline Module *getParent() { return Parent; }
  inline const Module *getParent() const { return Parent; }

  // Methods for support type inquiry through isa, cast, and dyn_cast:
  static inline bool classof(const Value *V) {
    return V->getValueID() == Value::FunctionVal ||
           V->getValueID() == Value::GlobalVariableVal ||
           V->getValueID() == Value::GlobalAliasVal;
  }
};

} // End llvm namespace

#endif