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 IR
11 // library.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/IR/GlobalValue.h"
16 #include "llvm/ADT/SmallPtrSet.h"
17 #include "llvm/IR/Constants.h"
18 #include "llvm/IR/DerivedTypes.h"
19 #include "llvm/IR/GlobalAlias.h"
20 #include "llvm/IR/GlobalVariable.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/Support/ErrorHandling.h"
23 #include "llvm/Support/LeakDetector.h"
24 using namespace llvm;
25
26 //===----------------------------------------------------------------------===//
27 // GlobalValue Class
28 //===----------------------------------------------------------------------===//
29
isMaterializable() const30 bool GlobalValue::isMaterializable() const {
31 return getParent() && getParent()->isMaterializable(this);
32 }
isDematerializable() const33 bool GlobalValue::isDematerializable() const {
34 return getParent() && getParent()->isDematerializable(this);
35 }
Materialize(std::string * ErrInfo)36 bool GlobalValue::Materialize(std::string *ErrInfo) {
37 return getParent()->Materialize(this, ErrInfo);
38 }
Dematerialize()39 void GlobalValue::Dematerialize() {
40 getParent()->Dematerialize(this);
41 }
42
43 /// Override destroyConstant to make sure it doesn't get called on
44 /// GlobalValue's because they shouldn't be treated like other constants.
destroyConstant()45 void GlobalValue::destroyConstant() {
46 llvm_unreachable("You can't GV->destroyConstant()!");
47 }
48
49 /// copyAttributesFrom - copy all additional attributes (those not needed to
50 /// create a GlobalValue) from the GlobalValue Src to this one.
copyAttributesFrom(const GlobalValue * Src)51 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
52 setAlignment(Src->getAlignment());
53 setSection(Src->getSection());
54 setVisibility(Src->getVisibility());
55 setUnnamedAddr(Src->hasUnnamedAddr());
56 }
57
setAlignment(unsigned Align)58 void GlobalValue::setAlignment(unsigned Align) {
59 assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
60 assert(Align <= MaximumAlignment &&
61 "Alignment is greater than MaximumAlignment!");
62 Alignment = Log2_32(Align) + 1;
63 assert(getAlignment() == Align && "Alignment representation error!");
64 }
65
isDeclaration() const66 bool GlobalValue::isDeclaration() const {
67 // Globals are definitions if they have an initializer.
68 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
69 return GV->getNumOperands() == 0;
70
71 // Functions are definitions if they have a body.
72 if (const Function *F = dyn_cast<Function>(this))
73 return F->empty();
74
75 // Aliases are always definitions.
76 assert(isa<GlobalAlias>(this));
77 return false;
78 }
79
80 //===----------------------------------------------------------------------===//
81 // GlobalVariable Implementation
82 //===----------------------------------------------------------------------===//
83
GlobalVariable(Type * Ty,bool constant,LinkageTypes Link,Constant * InitVal,const Twine & Name,ThreadLocalMode TLMode,unsigned AddressSpace,bool isExternallyInitialized)84 GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
85 Constant *InitVal,
86 const Twine &Name, ThreadLocalMode TLMode,
87 unsigned AddressSpace,
88 bool isExternallyInitialized)
89 : GlobalValue(PointerType::get(Ty, AddressSpace),
90 Value::GlobalVariableVal,
91 OperandTraits<GlobalVariable>::op_begin(this),
92 InitVal != 0, Link, Name),
93 isConstantGlobal(constant), threadLocalMode(TLMode),
94 isExternallyInitializedConstant(isExternallyInitialized) {
95 if (InitVal) {
96 assert(InitVal->getType() == Ty &&
97 "Initializer should be the same type as the GlobalVariable!");
98 Op<0>() = InitVal;
99 }
100
101 LeakDetector::addGarbageObject(this);
102 }
103
GlobalVariable(Module & M,Type * Ty,bool constant,LinkageTypes Link,Constant * InitVal,const Twine & Name,GlobalVariable * Before,ThreadLocalMode TLMode,unsigned AddressSpace,bool isExternallyInitialized)104 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
105 LinkageTypes Link, Constant *InitVal,
106 const Twine &Name,
107 GlobalVariable *Before, ThreadLocalMode TLMode,
108 unsigned AddressSpace,
109 bool isExternallyInitialized)
110 : GlobalValue(PointerType::get(Ty, AddressSpace),
111 Value::GlobalVariableVal,
112 OperandTraits<GlobalVariable>::op_begin(this),
113 InitVal != 0, Link, Name),
114 isConstantGlobal(constant), threadLocalMode(TLMode),
115 isExternallyInitializedConstant(isExternallyInitialized) {
116 if (InitVal) {
117 assert(InitVal->getType() == Ty &&
118 "Initializer should be the same type as the GlobalVariable!");
119 Op<0>() = InitVal;
120 }
121
122 LeakDetector::addGarbageObject(this);
123
124 if (Before)
125 Before->getParent()->getGlobalList().insert(Before, this);
126 else
127 M.getGlobalList().push_back(this);
128 }
129
setParent(Module * parent)130 void GlobalVariable::setParent(Module *parent) {
131 if (getParent())
132 LeakDetector::addGarbageObject(this);
133 Parent = parent;
134 if (getParent())
135 LeakDetector::removeGarbageObject(this);
136 }
137
removeFromParent()138 void GlobalVariable::removeFromParent() {
139 getParent()->getGlobalList().remove(this);
140 }
141
eraseFromParent()142 void GlobalVariable::eraseFromParent() {
143 getParent()->getGlobalList().erase(this);
144 }
145
replaceUsesOfWithOnConstant(Value * From,Value * To,Use * U)146 void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
147 Use *U) {
148 // If you call this, then you better know this GVar has a constant
149 // initializer worth replacing. Enforce that here.
150 assert(getNumOperands() == 1 &&
151 "Attempt to replace uses of Constants on a GVar with no initializer");
152
153 // And, since you know it has an initializer, the From value better be
154 // the initializer :)
155 assert(getOperand(0) == From &&
156 "Attempt to replace wrong constant initializer in GVar");
157
158 // And, you better have a constant for the replacement value
159 assert(isa<Constant>(To) &&
160 "Attempt to replace GVar initializer with non-constant");
161
162 // Okay, preconditions out of the way, replace the constant initializer.
163 this->setOperand(0, cast<Constant>(To));
164 }
165
setInitializer(Constant * InitVal)166 void GlobalVariable::setInitializer(Constant *InitVal) {
167 if (InitVal == 0) {
168 if (hasInitializer()) {
169 Op<0>().set(0);
170 NumOperands = 0;
171 }
172 } else {
173 assert(InitVal->getType() == getType()->getElementType() &&
174 "Initializer type must match GlobalVariable type");
175 if (!hasInitializer())
176 NumOperands = 1;
177 Op<0>().set(InitVal);
178 }
179 }
180
181 /// copyAttributesFrom - copy all additional attributes (those not needed to
182 /// create a GlobalVariable) from the GlobalVariable Src to this one.
copyAttributesFrom(const GlobalValue * Src)183 void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
184 assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!");
185 GlobalValue::copyAttributesFrom(Src);
186 const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
187 setThreadLocal(SrcVar->isThreadLocal());
188 }
189
190
191 //===----------------------------------------------------------------------===//
192 // GlobalAlias Implementation
193 //===----------------------------------------------------------------------===//
194
GlobalAlias(Type * Ty,LinkageTypes Link,const Twine & Name,Constant * aliasee,Module * ParentModule)195 GlobalAlias::GlobalAlias(Type *Ty, LinkageTypes Link,
196 const Twine &Name, Constant* aliasee,
197 Module *ParentModule)
198 : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) {
199 LeakDetector::addGarbageObject(this);
200
201 if (aliasee)
202 assert(aliasee->getType() == Ty && "Alias and aliasee types should match!");
203 Op<0>() = aliasee;
204
205 if (ParentModule)
206 ParentModule->getAliasList().push_back(this);
207 }
208
setParent(Module * parent)209 void GlobalAlias::setParent(Module *parent) {
210 if (getParent())
211 LeakDetector::addGarbageObject(this);
212 Parent = parent;
213 if (getParent())
214 LeakDetector::removeGarbageObject(this);
215 }
216
removeFromParent()217 void GlobalAlias::removeFromParent() {
218 getParent()->getAliasList().remove(this);
219 }
220
eraseFromParent()221 void GlobalAlias::eraseFromParent() {
222 getParent()->getAliasList().erase(this);
223 }
224
setAliasee(Constant * Aliasee)225 void GlobalAlias::setAliasee(Constant *Aliasee) {
226 assert((!Aliasee || Aliasee->getType() == getType()) &&
227 "Alias and aliasee types should match!");
228
229 setOperand(0, Aliasee);
230 }
231
getAliasedGlobal() const232 const GlobalValue *GlobalAlias::getAliasedGlobal() const {
233 const Constant *C = getAliasee();
234 if (C == 0) return 0;
235
236 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
237 return GV;
238
239 const ConstantExpr *CE = cast<ConstantExpr>(C);
240 assert((CE->getOpcode() == Instruction::BitCast ||
241 CE->getOpcode() == Instruction::GetElementPtr) &&
242 "Unsupported aliasee");
243
244 return cast<GlobalValue>(CE->getOperand(0));
245 }
246
resolveAliasedGlobal(bool stopOnWeak) const247 const GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) const {
248 SmallPtrSet<const GlobalValue*, 3> Visited;
249
250 // Check if we need to stop early.
251 if (stopOnWeak && mayBeOverridden())
252 return this;
253
254 const GlobalValue *GV = getAliasedGlobal();
255 Visited.insert(GV);
256
257 // Iterate over aliasing chain, stopping on weak alias if necessary.
258 while (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV)) {
259 if (stopOnWeak && GA->mayBeOverridden())
260 break;
261
262 GV = GA->getAliasedGlobal();
263
264 if (!Visited.insert(GV))
265 return 0;
266 }
267
268 return GV;
269 }
270