1 //===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the GlobalValue & GlobalVariable classes for the VMCore
11 // library.
12 //
13 //===----------------------------------------------------------------------===//
14
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"
23 using namespace llvm;
24
25 //===----------------------------------------------------------------------===//
26 // GlobalValue Class
27 //===----------------------------------------------------------------------===//
28
isMaterializable() const29 bool GlobalValue::isMaterializable() const {
30 return getParent() && getParent()->isMaterializable(this);
31 }
isDematerializable() const32 bool GlobalValue::isDematerializable() const {
33 return getParent() && getParent()->isDematerializable(this);
34 }
Materialize(std::string * ErrInfo)35 bool GlobalValue::Materialize(std::string *ErrInfo) {
36 return getParent()->Materialize(this, ErrInfo);
37 }
Dematerialize()38 void GlobalValue::Dematerialize() {
39 getParent()->Dematerialize(this);
40 }
41
42 /// Override destroyConstant to make sure it doesn't get called on
43 /// GlobalValue's because they shouldn't be treated like other constants.
destroyConstant()44 void GlobalValue::destroyConstant() {
45 llvm_unreachable("You can't GV->destroyConstant()!");
46 }
47
48 /// copyAttributesFrom - copy all additional attributes (those not needed to
49 /// create a GlobalValue) from the GlobalValue Src to this one.
copyAttributesFrom(const GlobalValue * Src)50 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
51 setAlignment(Src->getAlignment());
52 setSection(Src->getSection());
53 setVisibility(Src->getVisibility());
54 setUnnamedAddr(Src->hasUnnamedAddr());
55 }
56
setAlignment(unsigned Align)57 void GlobalValue::setAlignment(unsigned Align) {
58 assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
59 assert(Align <= MaximumAlignment &&
60 "Alignment is greater than MaximumAlignment!");
61 Alignment = Log2_32(Align) + 1;
62 assert(getAlignment() == Align && "Alignment representation error!");
63 }
64
isDeclaration() const65 bool GlobalValue::isDeclaration() const {
66 // Globals are definitions if they have an initializer.
67 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
68 return GV->getNumOperands() == 0;
69
70 // Functions are definitions if they have a body.
71 if (const Function *F = dyn_cast<Function>(this))
72 return F->empty();
73
74 // Aliases are always definitions.
75 assert(isa<GlobalAlias>(this));
76 return false;
77 }
78
79 //===----------------------------------------------------------------------===//
80 // GlobalVariable Implementation
81 //===----------------------------------------------------------------------===//
82
GlobalVariable(Type * Ty,bool constant,LinkageTypes Link,Constant * InitVal,const Twine & Name,bool ThreadLocal,unsigned AddressSpace)83 GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
84 Constant *InitVal, const Twine &Name,
85 bool ThreadLocal, unsigned AddressSpace)
86 : GlobalValue(PointerType::get(Ty, AddressSpace),
87 Value::GlobalVariableVal,
88 OperandTraits<GlobalVariable>::op_begin(this),
89 InitVal != 0, Link, Name),
90 isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
91 if (InitVal) {
92 assert(InitVal->getType() == Ty &&
93 "Initializer should be the same type as the GlobalVariable!");
94 Op<0>() = InitVal;
95 }
96
97 LeakDetector::addGarbageObject(this);
98 }
99
GlobalVariable(Module & M,Type * Ty,bool constant,LinkageTypes Link,Constant * InitVal,const Twine & Name,GlobalVariable * Before,bool ThreadLocal,unsigned AddressSpace)100 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
101 LinkageTypes Link, Constant *InitVal,
102 const Twine &Name,
103 GlobalVariable *Before, bool ThreadLocal,
104 unsigned AddressSpace)
105 : GlobalValue(PointerType::get(Ty, AddressSpace),
106 Value::GlobalVariableVal,
107 OperandTraits<GlobalVariable>::op_begin(this),
108 InitVal != 0, Link, Name),
109 isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
110 if (InitVal) {
111 assert(InitVal->getType() == Ty &&
112 "Initializer should be the same type as the GlobalVariable!");
113 Op<0>() = InitVal;
114 }
115
116 LeakDetector::addGarbageObject(this);
117
118 if (Before)
119 Before->getParent()->getGlobalList().insert(Before, this);
120 else
121 M.getGlobalList().push_back(this);
122 }
123
setParent(Module * parent)124 void GlobalVariable::setParent(Module *parent) {
125 if (getParent())
126 LeakDetector::addGarbageObject(this);
127 Parent = parent;
128 if (getParent())
129 LeakDetector::removeGarbageObject(this);
130 }
131
removeFromParent()132 void GlobalVariable::removeFromParent() {
133 getParent()->getGlobalList().remove(this);
134 }
135
eraseFromParent()136 void GlobalVariable::eraseFromParent() {
137 getParent()->getGlobalList().erase(this);
138 }
139
replaceUsesOfWithOnConstant(Value * From,Value * To,Use * U)140 void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
141 Use *U) {
142 // If you call this, then you better know this GVar has a constant
143 // initializer worth replacing. Enforce that here.
144 assert(getNumOperands() == 1 &&
145 "Attempt to replace uses of Constants on a GVar with no initializer");
146
147 // And, since you know it has an initializer, the From value better be
148 // the initializer :)
149 assert(getOperand(0) == From &&
150 "Attempt to replace wrong constant initializer in GVar");
151
152 // And, you better have a constant for the replacement value
153 assert(isa<Constant>(To) &&
154 "Attempt to replace GVar initializer with non-constant");
155
156 // Okay, preconditions out of the way, replace the constant initializer.
157 this->setOperand(0, cast<Constant>(To));
158 }
159
setInitializer(Constant * InitVal)160 void GlobalVariable::setInitializer(Constant *InitVal) {
161 if (InitVal == 0) {
162 if (hasInitializer()) {
163 Op<0>().set(0);
164 NumOperands = 0;
165 }
166 } else {
167 assert(InitVal->getType() == getType()->getElementType() &&
168 "Initializer type must match GlobalVariable type");
169 if (!hasInitializer())
170 NumOperands = 1;
171 Op<0>().set(InitVal);
172 }
173 }
174
175 /// copyAttributesFrom - copy all additional attributes (those not needed to
176 /// create a GlobalVariable) from the GlobalVariable Src to this one.
copyAttributesFrom(const GlobalValue * Src)177 void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
178 assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!");
179 GlobalValue::copyAttributesFrom(Src);
180 const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
181 setThreadLocal(SrcVar->isThreadLocal());
182 }
183
184
185 //===----------------------------------------------------------------------===//
186 // GlobalAlias Implementation
187 //===----------------------------------------------------------------------===//
188
GlobalAlias(Type * Ty,LinkageTypes Link,const Twine & Name,Constant * aliasee,Module * ParentModule)189 GlobalAlias::GlobalAlias(Type *Ty, LinkageTypes Link,
190 const Twine &Name, Constant* aliasee,
191 Module *ParentModule)
192 : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) {
193 LeakDetector::addGarbageObject(this);
194
195 if (aliasee)
196 assert(aliasee->getType() == Ty && "Alias and aliasee types should match!");
197 Op<0>() = aliasee;
198
199 if (ParentModule)
200 ParentModule->getAliasList().push_back(this);
201 }
202
setParent(Module * parent)203 void GlobalAlias::setParent(Module *parent) {
204 if (getParent())
205 LeakDetector::addGarbageObject(this);
206 Parent = parent;
207 if (getParent())
208 LeakDetector::removeGarbageObject(this);
209 }
210
removeFromParent()211 void GlobalAlias::removeFromParent() {
212 getParent()->getAliasList().remove(this);
213 }
214
eraseFromParent()215 void GlobalAlias::eraseFromParent() {
216 getParent()->getAliasList().erase(this);
217 }
218
setAliasee(Constant * Aliasee)219 void GlobalAlias::setAliasee(Constant *Aliasee) {
220 assert((!Aliasee || Aliasee->getType() == getType()) &&
221 "Alias and aliasee types should match!");
222
223 setOperand(0, Aliasee);
224 }
225
getAliasedGlobal() const226 const GlobalValue *GlobalAlias::getAliasedGlobal() const {
227 const Constant *C = getAliasee();
228 if (C == 0) return 0;
229
230 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
231 return GV;
232
233 const ConstantExpr *CE = cast<ConstantExpr>(C);
234 assert((CE->getOpcode() == Instruction::BitCast ||
235 CE->getOpcode() == Instruction::GetElementPtr) &&
236 "Unsupported aliasee");
237
238 return cast<GlobalValue>(CE->getOperand(0));
239 }
240
resolveAliasedGlobal(bool stopOnWeak) const241 const GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) const {
242 SmallPtrSet<const GlobalValue*, 3> Visited;
243
244 // Check if we need to stop early.
245 if (stopOnWeak && mayBeOverridden())
246 return this;
247
248 const GlobalValue *GV = getAliasedGlobal();
249 Visited.insert(GV);
250
251 // Iterate over aliasing chain, stopping on weak alias if necessary.
252 while (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV)) {
253 if (stopOnWeak && GA->mayBeOverridden())
254 break;
255
256 GV = GA->getAliasedGlobal();
257
258 if (!Visited.insert(GV))
259 return 0;
260 }
261
262 return GV;
263 }
264