1 //===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===//
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 implements the GlobalValue & GlobalVariable classes for the VMCore
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Constants.h"
16 #include "llvm/GlobalVariable.h"
17 #include "llvm/GlobalAlias.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/LLVMContext.h"
20 #include "llvm/Module.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/Support/LeakDetector.h"
25 //===----------------------------------------------------------------------===//
27 //===----------------------------------------------------------------------===//
29 /// removeDeadUsersOfConstant - If the specified constantexpr is dead, remove
30 /// it. This involves recursively eliminating any dead users of the
32 static bool removeDeadUsersOfConstant(const Constant *C) {
33 if (isa<GlobalValue>(C)) return false; // Cannot remove this
35 while (!C->use_empty()) {
36 const Constant *User = dyn_cast<Constant>(C->use_back());
37 if (!User) return false; // Non-constant usage;
38 if (!removeDeadUsersOfConstant(User))
39 return false; // Constant wasn't dead
42 const_cast<Constant*>(C)->destroyConstant();
46 /// removeDeadConstantUsers - If there are any dead constant users dangling
47 /// off of this global value, remove them. This method is useful for clients
48 /// that want to check to see if a global is unused, but don't want to deal
49 /// with potentially dead constants hanging off of the globals.
50 void GlobalValue::removeDeadConstantUsers() const {
51 Value::use_const_iterator I = use_begin(), E = use_end();
52 Value::use_const_iterator LastNonDeadUser = E;
54 if (const Constant *User = dyn_cast<Constant>(*I)) {
55 if (!removeDeadUsersOfConstant(User)) {
56 // If the constant wasn't dead, remember that this was the last live use
57 // and move on to the next constant.
61 // If the constant was dead, then the iterator is invalidated.
62 if (LastNonDeadUser == E) {
77 /// Override destroyConstant to make sure it doesn't get called on
78 /// GlobalValue's because they shouldn't be treated like other constants.
79 void GlobalValue::destroyConstant() {
80 assert(0 && "You can't GV->destroyConstant()!");
84 /// copyAttributesFrom - copy all additional attributes (those not needed to
85 /// create a GlobalValue) from the GlobalValue Src to this one.
86 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
87 setAlignment(Src->getAlignment());
88 setSection(Src->getSection());
89 setVisibility(Src->getVisibility());
93 //===----------------------------------------------------------------------===//
94 // GlobalVariable Implementation
95 //===----------------------------------------------------------------------===//
97 GlobalVariable::GlobalVariable(LLVMContext &Context, const Type *Ty,
98 bool constant, LinkageTypes Link,
99 Constant *InitVal, const std::string &Name,
100 Module *ParentModule, bool ThreadLocal,
101 unsigned AddressSpace)
102 : GlobalValue(Context.getPointerType(Ty, AddressSpace),
103 Value::GlobalVariableVal,
104 OperandTraits<GlobalVariable>::op_begin(this),
105 InitVal != 0, Link, Name),
106 isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
108 assert(InitVal->getType() == Ty &&
109 "Initializer should be the same type as the GlobalVariable!");
113 LeakDetector::addGarbageObject(this);
116 ParentModule->getGlobalList().push_back(this);
119 GlobalVariable::GlobalVariable(LLVMContext &Context, const Type *Ty,
120 bool constant, LinkageTypes Link,
121 Constant *InitVal, const std::string &Name,
122 GlobalVariable *Before, bool ThreadLocal,
123 unsigned AddressSpace)
124 : GlobalValue(Context.getPointerType(Ty, AddressSpace),
125 Value::GlobalVariableVal,
126 OperandTraits<GlobalVariable>::op_begin(this),
127 InitVal != 0, Link, Name),
128 isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
130 assert(InitVal->getType() == Ty &&
131 "Initializer should be the same type as the GlobalVariable!");
135 LeakDetector::addGarbageObject(this);
138 Before->getParent()->getGlobalList().insert(Before, this);
141 void GlobalVariable::setParent(Module *parent) {
143 LeakDetector::addGarbageObject(this);
146 LeakDetector::removeGarbageObject(this);
149 void GlobalVariable::removeFromParent() {
150 getParent()->getGlobalList().remove(this);
153 void GlobalVariable::eraseFromParent() {
154 getParent()->getGlobalList().erase(this);
157 void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
159 // If you call this, then you better know this GVar has a constant
160 // initializer worth replacing. Enforce that here.
161 assert(getNumOperands() == 1 &&
162 "Attempt to replace uses of Constants on a GVar with no initializer");
164 // And, since you know it has an initializer, the From value better be
165 // the initializer :)
166 assert(getOperand(0) == From &&
167 "Attempt to replace wrong constant initializer in GVar");
169 // And, you better have a constant for the replacement value
170 assert(isa<Constant>(To) &&
171 "Attempt to replace GVar initializer with non-constant");
173 // Okay, preconditions out of the way, replace the constant initializer.
174 this->setOperand(0, cast<Constant>(To));
177 /// copyAttributesFrom - copy all additional attributes (those not needed to
178 /// create a GlobalVariable) from the GlobalVariable Src to this one.
179 void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
180 assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!");
181 GlobalValue::copyAttributesFrom(Src);
182 const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
183 setThreadLocal(SrcVar->isThreadLocal());
187 //===----------------------------------------------------------------------===//
188 // GlobalAlias Implementation
189 //===----------------------------------------------------------------------===//
191 GlobalAlias::GlobalAlias(const Type *Ty, LinkageTypes Link,
192 const std::string &Name, Constant* aliasee,
193 Module *ParentModule)
194 : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) {
195 LeakDetector::addGarbageObject(this);
198 assert(aliasee->getType() == Ty && "Alias and aliasee types should match!");
202 ParentModule->getAliasList().push_back(this);
205 void GlobalAlias::setParent(Module *parent) {
207 LeakDetector::addGarbageObject(this);
210 LeakDetector::removeGarbageObject(this);
213 void GlobalAlias::removeFromParent() {
214 getParent()->getAliasList().remove(this);
217 void GlobalAlias::eraseFromParent() {
218 getParent()->getAliasList().erase(this);
221 bool GlobalAlias::isDeclaration() const {
222 const GlobalValue* AV = getAliasedGlobal();
224 return AV->isDeclaration();
229 void GlobalAlias::setAliasee(Constant *Aliasee)
232 assert(Aliasee->getType() == getType() &&
233 "Alias and aliasee types should match!");
235 setOperand(0, Aliasee);
238 const GlobalValue *GlobalAlias::getAliasedGlobal() const {
239 const Constant *C = getAliasee();
241 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
244 const ConstantExpr *CE = 0;
245 if ((CE = dyn_cast<ConstantExpr>(C)) &&
246 (CE->getOpcode() == Instruction::BitCast ||
247 CE->getOpcode() == Instruction::GetElementPtr))
248 return dyn_cast<GlobalValue>(CE->getOperand(0));
250 assert(0 && "Unsupported aliasee");
256 const GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) const {
257 SmallPtrSet<const GlobalValue*, 3> Visited;
259 // Check if we need to stop early.
260 if (stopOnWeak && mayBeOverridden())
263 const GlobalValue *GV = getAliasedGlobal();
266 // Iterate over aliasing chain, stopping on weak alias if necessary.
267 while (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV)) {
268 if (stopOnWeak && GA->mayBeOverridden())
271 GV = GA->getAliasedGlobal();
273 if (!Visited.insert(GV))