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/Support/LeakDetector.h"
23 //===----------------------------------------------------------------------===//
25 //===----------------------------------------------------------------------===//
27 /// removeDeadUsersOfConstant - If the specified constantexpr is dead, remove
28 /// it. This involves recursively eliminating any dead users of the
30 static bool removeDeadUsersOfConstant(Constant *C) {
31 if (isa<GlobalValue>(C)) return false; // Cannot remove this
33 while (!C->use_empty()) {
34 Constant *User = dyn_cast<Constant>(C->use_back());
35 if (!User) return false; // Non-constant usage;
36 if (!removeDeadUsersOfConstant(User))
37 return false; // Constant wasn't dead
44 /// removeDeadConstantUsers - If there are any dead constant users dangling
45 /// off of this global value, remove them. This method is useful for clients
46 /// that want to check to see if a global is unused, but don't want to deal
47 /// with potentially dead constants hanging off of the globals.
48 void GlobalValue::removeDeadConstantUsers() {
49 Value::use_iterator I = use_begin(), E = use_end();
50 Value::use_iterator LastNonDeadUser = E;
52 if (Constant *User = dyn_cast<Constant>(*I)) {
53 if (!removeDeadUsersOfConstant(User)) {
54 // If the constant wasn't dead, remember that this was the last live use
55 // and move on to the next constant.
59 // If the constant was dead, then the iterator is invalidated.
60 if (LastNonDeadUser == E) {
75 /// Override destroyConstant to make sure it doesn't get called on
76 /// GlobalValue's because they shouldn't be treated like other constants.
77 void GlobalValue::destroyConstant() {
78 assert(0 && "You can't GV->destroyConstant()!");
82 //===----------------------------------------------------------------------===//
83 // GlobalVariable Implementation
84 //===----------------------------------------------------------------------===//
86 GlobalVariable::GlobalVariable(const Type *Ty, bool constant, LinkageTypes Link,
87 Constant *InitVal, const std::string &Name,
88 Module *ParentModule, bool ThreadLocal,
89 unsigned AddressSpace)
90 : GlobalValue(PointerType::get(Ty, AddressSpace), Value::GlobalVariableVal,
91 &Initializer, InitVal != 0, Link, Name),
92 isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
94 assert(InitVal->getType() == Ty &&
95 "Initializer should be the same type as the GlobalVariable!");
96 Initializer.init(InitVal, this);
98 Initializer.init(0, this);
101 LeakDetector::addGarbageObject(this);
104 ParentModule->getGlobalList().push_back(this);
107 GlobalVariable::GlobalVariable(const Type *Ty, bool constant, LinkageTypes Link,
108 Constant *InitVal, const std::string &Name,
109 GlobalVariable *Before, bool ThreadLocal,
110 unsigned AddressSpace)
111 : GlobalValue(PointerType::get(Ty, AddressSpace), Value::GlobalVariableVal,
112 &Initializer, InitVal != 0, Link, Name),
113 isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
115 assert(InitVal->getType() == Ty &&
116 "Initializer should be the same type as the GlobalVariable!");
117 Initializer.init(InitVal, this);
119 Initializer.init(0, this);
122 LeakDetector::addGarbageObject(this);
125 Before->getParent()->getGlobalList().insert(Before, this);
128 void GlobalVariable::setParent(Module *parent) {
130 LeakDetector::addGarbageObject(this);
133 LeakDetector::removeGarbageObject(this);
136 void GlobalVariable::removeFromParent() {
137 getParent()->getGlobalList().remove(this);
140 void GlobalVariable::eraseFromParent() {
141 getParent()->getGlobalList().erase(this);
144 void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
146 // If you call this, then you better know this GVar has a constant
147 // initializer worth replacing. Enforce that here.
148 assert(getNumOperands() == 1 &&
149 "Attempt to replace uses of Constants on a GVar with no initializer");
151 // And, since you know it has an initializer, the From value better be
152 // the initializer :)
153 assert(getOperand(0) == From &&
154 "Attempt to replace wrong constant initializer in GVar");
156 // And, you better have a constant for the replacement value
157 assert(isa<Constant>(To) &&
158 "Attempt to replace GVar initializer with non-constant");
160 // Okay, preconditions out of the way, replace the constant initializer.
161 this->setOperand(0, cast<Constant>(To));
164 //===----------------------------------------------------------------------===//
165 // GlobalAlias Implementation
166 //===----------------------------------------------------------------------===//
168 GlobalAlias::GlobalAlias(const Type *Ty, LinkageTypes Link,
169 const std::string &Name, Constant* aliasee,
170 Module *ParentModule)
171 : GlobalValue(Ty, Value::GlobalAliasVal, &Aliasee, 1, Link, Name) {
172 LeakDetector::addGarbageObject(this);
175 assert(aliasee->getType() == Ty && "Alias and aliasee types should match!");
176 Aliasee.init(aliasee, this);
179 ParentModule->getAliasList().push_back(this);
182 void GlobalAlias::setParent(Module *parent) {
184 LeakDetector::addGarbageObject(this);
187 LeakDetector::removeGarbageObject(this);
190 void GlobalAlias::removeFromParent() {
191 getParent()->getAliasList().remove(this);
194 void GlobalAlias::eraseFromParent() {
195 getParent()->getAliasList().erase(this);
198 bool GlobalAlias::isDeclaration() const {
199 const GlobalValue* AV = getAliasedGlobal();
201 return AV->isDeclaration();
206 void GlobalAlias::setAliasee(Constant *Aliasee)
209 assert(Aliasee->getType() == getType() &&
210 "Alias and aliasee types should match!");
212 setOperand(0, Aliasee);
215 const GlobalValue *GlobalAlias::getAliasedGlobal() const {
216 const Constant *C = getAliasee();
218 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
221 const ConstantExpr *CE = 0;
222 if ((CE = dyn_cast<ConstantExpr>(C)) &&
223 (CE->getOpcode() == Instruction::BitCast ||
224 CE->getOpcode() == Instruction::GetElementPtr))
225 return dyn_cast<GlobalValue>(CE->getOperand(0));
227 assert(0 && "Unsupported aliasee");