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/Module.h"
20 #include "llvm/ADT/SmallPtrSet.h"
21 #include "llvm/Support/ErrorHandling.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 bool GlobalValue::isMaterializable() const {
47 return getParent() && getParent()->isMaterializable(this);
49 bool GlobalValue::isDematerializable() const {
50 return getParent() && getParent()->isDematerializable(this);
52 bool GlobalValue::Materialize(std::string *ErrInfo) {
53 return getParent()->Materialize(this, ErrInfo);
55 void GlobalValue::Dematerialize() {
56 getParent()->Dematerialize(this);
59 /// removeDeadConstantUsers - If there are any dead constant users dangling
60 /// off of this global value, remove them. This method is useful for clients
61 /// that want to check to see if a global is unused, but don't want to deal
62 /// with potentially dead constants hanging off of the globals.
63 void GlobalValue::removeDeadConstantUsers() const {
64 Value::const_use_iterator I = use_begin(), E = use_end();
65 Value::const_use_iterator LastNonDeadUser = E;
67 if (const Constant *User = dyn_cast<Constant>(*I)) {
68 if (!removeDeadUsersOfConstant(User)) {
69 // If the constant wasn't dead, remember that this was the last live use
70 // and move on to the next constant.
74 // If the constant was dead, then the iterator is invalidated.
75 if (LastNonDeadUser == E) {
91 /// Override destroyConstant to make sure it doesn't get called on
92 /// GlobalValue's because they shouldn't be treated like other constants.
93 void GlobalValue::destroyConstant() {
94 llvm_unreachable("You can't GV->destroyConstant()!");
97 /// copyAttributesFrom - copy all additional attributes (those not needed to
98 /// create a GlobalValue) from the GlobalValue Src to this one.
99 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
100 setAlignment(Src->getAlignment());
101 setSection(Src->getSection());
102 setVisibility(Src->getVisibility());
106 //===----------------------------------------------------------------------===//
107 // GlobalVariable Implementation
108 //===----------------------------------------------------------------------===//
110 GlobalVariable::GlobalVariable(const Type *Ty, bool constant, LinkageTypes Link,
111 Constant *InitVal, const Twine &Name,
112 bool ThreadLocal, unsigned AddressSpace)
113 : GlobalValue(PointerType::get(Ty, AddressSpace),
114 Value::GlobalVariableVal,
115 OperandTraits<GlobalVariable>::op_begin(this),
116 InitVal != 0, Link, Name),
117 isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
119 assert(InitVal->getType() == Ty &&
120 "Initializer should be the same type as the GlobalVariable!");
124 LeakDetector::addGarbageObject(this);
127 GlobalVariable::GlobalVariable(Module &M, const Type *Ty, bool constant,
128 LinkageTypes Link, Constant *InitVal,
130 GlobalVariable *Before, bool ThreadLocal,
131 unsigned AddressSpace)
132 : GlobalValue(PointerType::get(Ty, AddressSpace),
133 Value::GlobalVariableVal,
134 OperandTraits<GlobalVariable>::op_begin(this),
135 InitVal != 0, Link, Name),
136 isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
138 assert(InitVal->getType() == Ty &&
139 "Initializer should be the same type as the GlobalVariable!");
143 LeakDetector::addGarbageObject(this);
146 Before->getParent()->getGlobalList().insert(Before, this);
148 M.getGlobalList().push_back(this);
151 void GlobalVariable::setParent(Module *parent) {
153 LeakDetector::addGarbageObject(this);
156 LeakDetector::removeGarbageObject(this);
159 void GlobalVariable::removeFromParent() {
160 getParent()->getGlobalList().remove(this);
163 void GlobalVariable::eraseFromParent() {
164 getParent()->getGlobalList().erase(this);
167 void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
169 // If you call this, then you better know this GVar has a constant
170 // initializer worth replacing. Enforce that here.
171 assert(getNumOperands() == 1 &&
172 "Attempt to replace uses of Constants on a GVar with no initializer");
174 // And, since you know it has an initializer, the From value better be
175 // the initializer :)
176 assert(getOperand(0) == From &&
177 "Attempt to replace wrong constant initializer in GVar");
179 // And, you better have a constant for the replacement value
180 assert(isa<Constant>(To) &&
181 "Attempt to replace GVar initializer with non-constant");
183 // Okay, preconditions out of the way, replace the constant initializer.
184 this->setOperand(0, cast<Constant>(To));
187 void GlobalVariable::setInitializer(Constant *InitVal) {
189 if (hasInitializer()) {
194 assert(InitVal->getType() == getType()->getElementType() &&
195 "Initializer type must match GlobalVariable type");
196 if (!hasInitializer())
198 Op<0>().set(InitVal);
202 /// copyAttributesFrom - copy all additional attributes (those not needed to
203 /// create a GlobalVariable) from the GlobalVariable Src to this one.
204 void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
205 assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!");
206 GlobalValue::copyAttributesFrom(Src);
207 const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
208 setThreadLocal(SrcVar->isThreadLocal());
212 //===----------------------------------------------------------------------===//
213 // GlobalAlias Implementation
214 //===----------------------------------------------------------------------===//
216 GlobalAlias::GlobalAlias(const Type *Ty, LinkageTypes Link,
217 const Twine &Name, Constant* aliasee,
218 Module *ParentModule)
219 : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) {
220 LeakDetector::addGarbageObject(this);
223 assert(aliasee->getType() == Ty && "Alias and aliasee types should match!");
227 ParentModule->getAliasList().push_back(this);
230 void GlobalAlias::setParent(Module *parent) {
232 LeakDetector::addGarbageObject(this);
235 LeakDetector::removeGarbageObject(this);
238 void GlobalAlias::removeFromParent() {
239 getParent()->getAliasList().remove(this);
242 void GlobalAlias::eraseFromParent() {
243 getParent()->getAliasList().erase(this);
246 bool GlobalAlias::isDeclaration() const {
247 const GlobalValue* AV = getAliasedGlobal();
249 return AV->isDeclaration();
254 void GlobalAlias::setAliasee(Constant *Aliasee)
257 assert(Aliasee->getType() == getType() &&
258 "Alias and aliasee types should match!");
260 setOperand(0, Aliasee);
263 const GlobalValue *GlobalAlias::getAliasedGlobal() const {
264 const Constant *C = getAliasee();
266 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
269 const ConstantExpr *CE = 0;
270 if ((CE = dyn_cast<ConstantExpr>(C)) &&
271 (CE->getOpcode() == Instruction::BitCast ||
272 CE->getOpcode() == Instruction::GetElementPtr))
273 return dyn_cast<GlobalValue>(CE->getOperand(0));
275 llvm_unreachable("Unsupported aliasee");
281 const GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) const {
282 SmallPtrSet<const GlobalValue*, 3> Visited;
284 // Check if we need to stop early.
285 if (stopOnWeak && mayBeOverridden())
288 const GlobalValue *GV = getAliasedGlobal();
291 // Iterate over aliasing chain, stopping on weak alias if necessary.
292 while (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV)) {
293 if (stopOnWeak && GA->mayBeOverridden())
296 GV = GA->getAliasedGlobal();
298 if (!Visited.insert(GV))