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/IR/Operator.h"
23 #include "llvm/Support/ErrorHandling.h"
24 using namespace llvm;
25
26 //===----------------------------------------------------------------------===//
27 // GlobalValue Class
28 //===----------------------------------------------------------------------===//
29
isMaterializable() const30 bool GlobalValue::isMaterializable() const {
31 if (const Function *F = dyn_cast<Function>(this))
32 return F->isMaterializable();
33 return false;
34 }
materialize()35 std::error_code GlobalValue::materialize() {
36 return getParent()->materialize(this);
37 }
38
39 /// Override destroyConstantImpl to make sure it doesn't get called on
40 /// GlobalValue's because they shouldn't be treated like other constants.
destroyConstantImpl()41 void GlobalValue::destroyConstantImpl() {
42 llvm_unreachable("You can't GV->destroyConstantImpl()!");
43 }
44
handleOperandChangeImpl(Value * From,Value * To,Use * U)45 Value *GlobalValue::handleOperandChangeImpl(Value *From, Value *To, Use *U) {
46 llvm_unreachable("Unsupported class for handleOperandChange()!");
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 setVisibility(Src->getVisibility());
53 setUnnamedAddr(Src->hasUnnamedAddr());
54 setDLLStorageClass(Src->getDLLStorageClass());
55 }
56
getAlignment() const57 unsigned GlobalValue::getAlignment() const {
58 if (auto *GA = dyn_cast<GlobalAlias>(this)) {
59 // In general we cannot compute this at the IR level, but we try.
60 if (const GlobalObject *GO = GA->getBaseObject())
61 return GO->getAlignment();
62
63 // FIXME: we should also be able to handle:
64 // Alias = Global + Offset
65 // Alias = Absolute
66 return 0;
67 }
68 return cast<GlobalObject>(this)->getAlignment();
69 }
70
setAlignment(unsigned Align)71 void GlobalObject::setAlignment(unsigned Align) {
72 assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
73 assert(Align <= MaximumAlignment &&
74 "Alignment is greater than MaximumAlignment!");
75 unsigned AlignmentData = Log2_32(Align) + 1;
76 unsigned OldData = getGlobalValueSubClassData();
77 setGlobalValueSubClassData((OldData & ~AlignmentMask) | AlignmentData);
78 assert(getAlignment() == Align && "Alignment representation error!");
79 }
80
getGlobalObjectSubClassData() const81 unsigned GlobalObject::getGlobalObjectSubClassData() const {
82 unsigned ValueData = getGlobalValueSubClassData();
83 return ValueData >> AlignmentBits;
84 }
85
setGlobalObjectSubClassData(unsigned Val)86 void GlobalObject::setGlobalObjectSubClassData(unsigned Val) {
87 unsigned OldData = getGlobalValueSubClassData();
88 setGlobalValueSubClassData((OldData & AlignmentMask) |
89 (Val << AlignmentBits));
90 assert(getGlobalObjectSubClassData() == Val && "representation error");
91 }
92
copyAttributesFrom(const GlobalValue * Src)93 void GlobalObject::copyAttributesFrom(const GlobalValue *Src) {
94 GlobalValue::copyAttributesFrom(Src);
95 if (const auto *GV = dyn_cast<GlobalObject>(Src)) {
96 setAlignment(GV->getAlignment());
97 setSection(GV->getSection());
98 }
99 }
100
getSection() const101 const char *GlobalValue::getSection() const {
102 if (auto *GA = dyn_cast<GlobalAlias>(this)) {
103 // In general we cannot compute this at the IR level, but we try.
104 if (const GlobalObject *GO = GA->getBaseObject())
105 return GO->getSection();
106 return "";
107 }
108 return cast<GlobalObject>(this)->getSection();
109 }
110
getComdat()111 Comdat *GlobalValue::getComdat() {
112 if (auto *GA = dyn_cast<GlobalAlias>(this)) {
113 // In general we cannot compute this at the IR level, but we try.
114 if (const GlobalObject *GO = GA->getBaseObject())
115 return const_cast<GlobalObject *>(GO)->getComdat();
116 return nullptr;
117 }
118 return cast<GlobalObject>(this)->getComdat();
119 }
120
setSection(StringRef S)121 void GlobalObject::setSection(StringRef S) { Section = S; }
122
isDeclaration() const123 bool GlobalValue::isDeclaration() const {
124 // Globals are definitions if they have an initializer.
125 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
126 return GV->getNumOperands() == 0;
127
128 // Functions are definitions if they have a body.
129 if (const Function *F = dyn_cast<Function>(this))
130 return F->empty() && !F->isMaterializable();
131
132 // Aliases are always definitions.
133 assert(isa<GlobalAlias>(this));
134 return false;
135 }
136
137 //===----------------------------------------------------------------------===//
138 // GlobalVariable Implementation
139 //===----------------------------------------------------------------------===//
140
GlobalVariable(Type * Ty,bool constant,LinkageTypes Link,Constant * InitVal,const Twine & Name,ThreadLocalMode TLMode,unsigned AddressSpace,bool isExternallyInitialized)141 GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
142 Constant *InitVal, const Twine &Name,
143 ThreadLocalMode TLMode, unsigned AddressSpace,
144 bool isExternallyInitialized)
145 : GlobalObject(Ty, Value::GlobalVariableVal,
146 OperandTraits<GlobalVariable>::op_begin(this),
147 InitVal != nullptr, Link, Name, AddressSpace),
148 isConstantGlobal(constant),
149 isExternallyInitializedConstant(isExternallyInitialized) {
150 setThreadLocalMode(TLMode);
151 if (InitVal) {
152 assert(InitVal->getType() == Ty &&
153 "Initializer should be the same type as the GlobalVariable!");
154 Op<0>() = InitVal;
155 }
156 }
157
GlobalVariable(Module & M,Type * Ty,bool constant,LinkageTypes Link,Constant * InitVal,const Twine & Name,GlobalVariable * Before,ThreadLocalMode TLMode,unsigned AddressSpace,bool isExternallyInitialized)158 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
159 LinkageTypes Link, Constant *InitVal,
160 const Twine &Name, GlobalVariable *Before,
161 ThreadLocalMode TLMode, unsigned AddressSpace,
162 bool isExternallyInitialized)
163 : GlobalObject(Ty, Value::GlobalVariableVal,
164 OperandTraits<GlobalVariable>::op_begin(this),
165 InitVal != nullptr, Link, Name, AddressSpace),
166 isConstantGlobal(constant),
167 isExternallyInitializedConstant(isExternallyInitialized) {
168 setThreadLocalMode(TLMode);
169 if (InitVal) {
170 assert(InitVal->getType() == Ty &&
171 "Initializer should be the same type as the GlobalVariable!");
172 Op<0>() = InitVal;
173 }
174
175 if (Before)
176 Before->getParent()->getGlobalList().insert(Before->getIterator(), this);
177 else
178 M.getGlobalList().push_back(this);
179 }
180
setParent(Module * parent)181 void GlobalVariable::setParent(Module *parent) {
182 Parent = parent;
183 }
184
removeFromParent()185 void GlobalVariable::removeFromParent() {
186 getParent()->getGlobalList().remove(getIterator());
187 }
188
eraseFromParent()189 void GlobalVariable::eraseFromParent() {
190 getParent()->getGlobalList().erase(getIterator());
191 }
192
setInitializer(Constant * InitVal)193 void GlobalVariable::setInitializer(Constant *InitVal) {
194 if (!InitVal) {
195 if (hasInitializer()) {
196 // Note, the num operands is used to compute the offset of the operand, so
197 // the order here matters. Clearing the operand then clearing the num
198 // operands ensures we have the correct offset to the operand.
199 Op<0>().set(nullptr);
200 setGlobalVariableNumOperands(0);
201 }
202 } else {
203 assert(InitVal->getType() == getType()->getElementType() &&
204 "Initializer type must match GlobalVariable type");
205 // Note, the num operands is used to compute the offset of the operand, so
206 // the order here matters. We need to set num operands to 1 first so that
207 // we get the correct offset to the first operand when we set it.
208 if (!hasInitializer())
209 setGlobalVariableNumOperands(1);
210 Op<0>().set(InitVal);
211 }
212 }
213
214 /// Copy all additional attributes (those not needed to create a GlobalVariable)
215 /// from the GlobalVariable Src to this one.
copyAttributesFrom(const GlobalValue * Src)216 void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
217 GlobalObject::copyAttributesFrom(Src);
218 if (const GlobalVariable *SrcVar = dyn_cast<GlobalVariable>(Src)) {
219 setThreadLocalMode(SrcVar->getThreadLocalMode());
220 setExternallyInitialized(SrcVar->isExternallyInitialized());
221 }
222 }
223
224
225 //===----------------------------------------------------------------------===//
226 // GlobalAlias Implementation
227 //===----------------------------------------------------------------------===//
228
GlobalAlias(Type * Ty,unsigned AddressSpace,LinkageTypes Link,const Twine & Name,Constant * Aliasee,Module * ParentModule)229 GlobalAlias::GlobalAlias(Type *Ty, unsigned AddressSpace, LinkageTypes Link,
230 const Twine &Name, Constant *Aliasee,
231 Module *ParentModule)
232 : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name,
233 AddressSpace) {
234 Op<0>() = Aliasee;
235
236 if (ParentModule)
237 ParentModule->getAliasList().push_back(this);
238 }
239
create(Type * Ty,unsigned AddressSpace,LinkageTypes Link,const Twine & Name,Constant * Aliasee,Module * ParentModule)240 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
241 LinkageTypes Link, const Twine &Name,
242 Constant *Aliasee, Module *ParentModule) {
243 return new GlobalAlias(Ty, AddressSpace, Link, Name, Aliasee, ParentModule);
244 }
245
create(Type * Ty,unsigned AddressSpace,LinkageTypes Linkage,const Twine & Name,Module * Parent)246 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
247 LinkageTypes Linkage, const Twine &Name,
248 Module *Parent) {
249 return create(Ty, AddressSpace, Linkage, Name, nullptr, Parent);
250 }
251
create(Type * Ty,unsigned AddressSpace,LinkageTypes Linkage,const Twine & Name,GlobalValue * Aliasee)252 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
253 LinkageTypes Linkage, const Twine &Name,
254 GlobalValue *Aliasee) {
255 return create(Ty, AddressSpace, Linkage, Name, Aliasee, Aliasee->getParent());
256 }
257
create(LinkageTypes Link,const Twine & Name,GlobalValue * Aliasee)258 GlobalAlias *GlobalAlias::create(LinkageTypes Link, const Twine &Name,
259 GlobalValue *Aliasee) {
260 PointerType *PTy = Aliasee->getType();
261 return create(PTy->getElementType(), PTy->getAddressSpace(), Link, Name,
262 Aliasee);
263 }
264
create(const Twine & Name,GlobalValue * Aliasee)265 GlobalAlias *GlobalAlias::create(const Twine &Name, GlobalValue *Aliasee) {
266 return create(Aliasee->getLinkage(), Name, Aliasee);
267 }
268
setParent(Module * parent)269 void GlobalAlias::setParent(Module *parent) {
270 Parent = parent;
271 }
272
removeFromParent()273 void GlobalAlias::removeFromParent() {
274 getParent()->getAliasList().remove(getIterator());
275 }
276
eraseFromParent()277 void GlobalAlias::eraseFromParent() {
278 getParent()->getAliasList().erase(getIterator());
279 }
280
setAliasee(Constant * Aliasee)281 void GlobalAlias::setAliasee(Constant *Aliasee) {
282 assert((!Aliasee || Aliasee->getType() == getType()) &&
283 "Alias and aliasee types should match!");
284 setOperand(0, Aliasee);
285 }
286