1 //===-- llvm/GlobalValue.h - Class to represent a global value --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a common base class of all globally definable objects. As such,
11 // it is subclassed by GlobalVariable, GlobalAlias and by Function. This is
12 // used because you can do certain things with these global objects that you
13 // can't do to anything else. For example, use the address of one as a
16 //===----------------------------------------------------------------------===//
18 #ifndef LLVM_GLOBALVALUE_H
19 #define LLVM_GLOBALVALUE_H
21 #include "llvm/Constant.h"
28 class GlobalValue : public Constant {
29 GlobalValue(const GlobalValue &); // do not implement
31 /// @brief An enumeration for the kinds of linkage for global values.
33 ExternalLinkage = 0,///< Externally visible function
34 AvailableExternallyLinkage, ///< Available for inspection, not emission.
35 LinkOnceAnyLinkage, ///< Keep one copy of function when linking (inline)
36 LinkOnceODRLinkage, ///< Same, but only replaced by something equivalent.
37 WeakAnyLinkage, ///< Keep one copy of named function when linking (weak)
38 WeakODRLinkage, ///< Same, but only replaced by something equivalent.
39 AppendingLinkage, ///< Special purpose, only applies to global arrays
40 InternalLinkage, ///< Rename collisions when linking (static functions).
41 PrivateLinkage, ///< Like Internal, but omit from symbol table.
42 LinkerPrivateLinkage, ///< Like Private, but linker removes.
43 LinkerPrivateWeakLinkage, ///< Like LinkerPrivate, but weak.
44 LinkerPrivateWeakDefAutoLinkage, ///< Like LinkerPrivateWeak, but possibly
46 DLLImportLinkage, ///< Function to be imported from DLL
47 DLLExportLinkage, ///< Function to be accessible from DLL.
48 ExternalWeakLinkage,///< ExternalWeak linkage description.
49 CommonLinkage ///< Tentative definitions.
52 /// @brief An enumeration for the kinds of visibility of global values.
53 enum VisibilityTypes {
54 DefaultVisibility = 0, ///< The GV is visible
55 HiddenVisibility, ///< The GV is hidden
56 ProtectedVisibility ///< The GV is protected
60 GlobalValue(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps,
61 LinkageTypes linkage, const Twine &Name)
62 : Constant(ty, vty, Ops, NumOps), Linkage(linkage),
63 Visibility(DefaultVisibility), Alignment(0), UnnamedAddr(0), Parent(0) {
67 // Note: VC++ treats enums as signed, so an extra bit is required to prevent
68 // Linkage and Visibility from turning into negative values.
69 LinkageTypes Linkage : 5; // The linkage of this global
70 unsigned Visibility : 2; // The visibility style of this global
71 unsigned Alignment : 16; // Alignment of this symbol, must be power of two
72 unsigned UnnamedAddr : 1; // This value's address is not significant
73 Module *Parent; // The containing module.
74 std::string Section; // Section to emit this into, empty mean default
77 removeDeadConstantUsers(); // remove any dead constants using this.
80 unsigned getAlignment() const {
81 return (1u << Alignment) >> 1;
83 void setAlignment(unsigned Align);
85 bool hasUnnamedAddr() const { return UnnamedAddr; }
86 void setUnnamedAddr(bool Val) { UnnamedAddr = Val; }
88 VisibilityTypes getVisibility() const { return VisibilityTypes(Visibility); }
89 bool hasDefaultVisibility() const { return Visibility == DefaultVisibility; }
90 bool hasHiddenVisibility() const { return Visibility == HiddenVisibility; }
91 bool hasProtectedVisibility() const {
92 return Visibility == ProtectedVisibility;
94 void setVisibility(VisibilityTypes V) { Visibility = V; }
96 bool hasSection() const { return !Section.empty(); }
97 const std::string &getSection() const { return Section; }
98 void setSection(StringRef S) { Section = S; }
100 /// If the usage is empty (except transitively dead constants), then this
101 /// global value can be safely deleted since the destructor will
102 /// delete the dead constants as well.
103 /// @brief Determine if the usage of this global value is empty except
104 /// for transitively dead constants.
105 bool use_empty_except_constants();
107 /// getType - Global values are always pointers.
108 inline PointerType *getType() const {
109 return reinterpret_cast<PointerType*>(User::getType());
112 static LinkageTypes getLinkOnceLinkage(bool ODR) {
113 return ODR ? LinkOnceODRLinkage : LinkOnceAnyLinkage;
115 static LinkageTypes getWeakLinkage(bool ODR) {
116 return ODR ? WeakODRLinkage : WeakAnyLinkage;
119 static bool isExternalLinkage(LinkageTypes Linkage) {
120 return Linkage == ExternalLinkage;
122 static bool isAvailableExternallyLinkage(LinkageTypes Linkage) {
123 return Linkage == AvailableExternallyLinkage;
125 static bool isLinkOnceLinkage(LinkageTypes Linkage) {
126 return Linkage == LinkOnceAnyLinkage || Linkage == LinkOnceODRLinkage;
128 static bool isWeakLinkage(LinkageTypes Linkage) {
129 return Linkage == WeakAnyLinkage || Linkage == WeakODRLinkage;
131 static bool isAppendingLinkage(LinkageTypes Linkage) {
132 return Linkage == AppendingLinkage;
134 static bool isInternalLinkage(LinkageTypes Linkage) {
135 return Linkage == InternalLinkage;
137 static bool isPrivateLinkage(LinkageTypes Linkage) {
138 return Linkage == PrivateLinkage;
140 static bool isLinkerPrivateLinkage(LinkageTypes Linkage) {
141 return Linkage == LinkerPrivateLinkage;
143 static bool isLinkerPrivateWeakLinkage(LinkageTypes Linkage) {
144 return Linkage == LinkerPrivateWeakLinkage;
146 static bool isLinkerPrivateWeakDefAutoLinkage(LinkageTypes Linkage) {
147 return Linkage == LinkerPrivateWeakDefAutoLinkage;
149 static bool isLocalLinkage(LinkageTypes Linkage) {
150 return isInternalLinkage(Linkage) || isPrivateLinkage(Linkage) ||
151 isLinkerPrivateLinkage(Linkage) || isLinkerPrivateWeakLinkage(Linkage) ||
152 isLinkerPrivateWeakDefAutoLinkage(Linkage);
154 static bool isDLLImportLinkage(LinkageTypes Linkage) {
155 return Linkage == DLLImportLinkage;
157 static bool isDLLExportLinkage(LinkageTypes Linkage) {
158 return Linkage == DLLExportLinkage;
160 static bool isExternalWeakLinkage(LinkageTypes Linkage) {
161 return Linkage == ExternalWeakLinkage;
163 static bool isCommonLinkage(LinkageTypes Linkage) {
164 return Linkage == CommonLinkage;
167 /// mayBeOverridden - Whether the definition of this global may be replaced
168 /// by something non-equivalent at link time. For example, if a function has
169 /// weak linkage then the code defining it may be replaced by different code.
170 static bool mayBeOverridden(LinkageTypes Linkage) {
171 return Linkage == WeakAnyLinkage ||
172 Linkage == LinkOnceAnyLinkage ||
173 Linkage == CommonLinkage ||
174 Linkage == ExternalWeakLinkage ||
175 Linkage == LinkerPrivateWeakLinkage ||
176 Linkage == LinkerPrivateWeakDefAutoLinkage;
179 /// isWeakForLinker - Whether the definition of this global may be replaced at
180 /// link time. NB: Using this method outside of the code generators is almost
181 /// always a mistake: when working at the IR level use mayBeOverridden instead
182 /// as it knows about ODR semantics.
183 static bool isWeakForLinker(LinkageTypes Linkage) {
184 return Linkage == AvailableExternallyLinkage ||
185 Linkage == WeakAnyLinkage ||
186 Linkage == WeakODRLinkage ||
187 Linkage == LinkOnceAnyLinkage ||
188 Linkage == LinkOnceODRLinkage ||
189 Linkage == CommonLinkage ||
190 Linkage == ExternalWeakLinkage ||
191 Linkage == LinkerPrivateWeakLinkage ||
192 Linkage == LinkerPrivateWeakDefAutoLinkage;
195 bool hasExternalLinkage() const { return isExternalLinkage(Linkage); }
196 bool hasAvailableExternallyLinkage() const {
197 return isAvailableExternallyLinkage(Linkage);
199 bool hasLinkOnceLinkage() const {
200 return isLinkOnceLinkage(Linkage);
202 bool hasWeakLinkage() const {
203 return isWeakLinkage(Linkage);
205 bool hasAppendingLinkage() const { return isAppendingLinkage(Linkage); }
206 bool hasInternalLinkage() const { return isInternalLinkage(Linkage); }
207 bool hasPrivateLinkage() const { return isPrivateLinkage(Linkage); }
208 bool hasLinkerPrivateLinkage() const { return isLinkerPrivateLinkage(Linkage); }
209 bool hasLinkerPrivateWeakLinkage() const {
210 return isLinkerPrivateWeakLinkage(Linkage);
212 bool hasLinkerPrivateWeakDefAutoLinkage() const {
213 return isLinkerPrivateWeakDefAutoLinkage(Linkage);
215 bool hasLocalLinkage() const { return isLocalLinkage(Linkage); }
216 bool hasDLLImportLinkage() const { return isDLLImportLinkage(Linkage); }
217 bool hasDLLExportLinkage() const { return isDLLExportLinkage(Linkage); }
218 bool hasExternalWeakLinkage() const { return isExternalWeakLinkage(Linkage); }
219 bool hasCommonLinkage() const { return isCommonLinkage(Linkage); }
221 void setLinkage(LinkageTypes LT) { Linkage = LT; }
222 LinkageTypes getLinkage() const { return Linkage; }
224 bool mayBeOverridden() const { return mayBeOverridden(Linkage); }
226 bool isWeakForLinker() const { return isWeakForLinker(Linkage); }
228 /// copyAttributesFrom - copy all additional attributes (those not needed to
229 /// create a GlobalValue) from the GlobalValue Src to this one.
230 virtual void copyAttributesFrom(const GlobalValue *Src);
232 /// @name Materialization
233 /// Materialization is used to construct functions only as they're needed. This
234 /// is useful to reduce memory usage in LLVM or parsing work done by the
235 /// BitcodeReader to load the Module.
238 /// isMaterializable - If this function's Module is being lazily streamed in
239 /// functions from disk or some other source, this method can be used to check
240 /// to see if the function has been read in yet or not.
241 bool isMaterializable() const;
243 /// isDematerializable - Returns true if this function was loaded from a
244 /// GVMaterializer that's still attached to its Module and that knows how to
245 /// dematerialize the function.
246 bool isDematerializable() const;
248 /// Materialize - make sure this GlobalValue is fully read. If the module is
249 /// corrupt, this returns true and fills in the optional string with
250 /// information about the problem. If successful, this returns false.
251 bool Materialize(std::string *ErrInfo = 0);
253 /// Dematerialize - If this GlobalValue is read in, and if the GVMaterializer
254 /// supports it, release the memory for the function, and set it up to be
255 /// materialized lazily. If !isDematerializable(), this method is a noop.
256 void Dematerialize();
260 /// Override from Constant class.
261 virtual void destroyConstant();
263 /// isDeclaration - Return true if the primary definition of this global
264 /// value is outside of the current translation unit.
265 bool isDeclaration() const;
267 /// removeFromParent - This method unlinks 'this' from the containing module,
268 /// but does not delete it.
269 virtual void removeFromParent() = 0;
271 /// eraseFromParent - This method unlinks 'this' from the containing module
273 virtual void eraseFromParent() = 0;
275 /// getParent - Get the module that this global value is contained inside
277 inline Module *getParent() { return Parent; }
278 inline const Module *getParent() const { return Parent; }
280 // Methods for support type inquiry through isa, cast, and dyn_cast:
281 static inline bool classof(const GlobalValue *) { return true; }
282 static inline bool classof(const Value *V) {
283 return V->getValueID() == Value::FunctionVal ||
284 V->getValueID() == Value::GlobalVariableVal ||
285 V->getValueID() == Value::GlobalAliasVal;
289 } // End llvm namespace