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 30 bool GlobalValue::isMaterializable() const { 31 if (const Function *F = dyn_cast<Function>(this)) 32 return F->isMaterializable(); 33 return false; 34 } 35 bool GlobalValue::isDematerializable() const { 36 return getParent() && getParent()->isDematerializable(this); 37 } 38 std::error_code GlobalValue::materialize() { 39 return getParent()->materialize(this); 40 } 41 void GlobalValue::dematerialize() { 42 getParent()->dematerialize(this); 43 } 44 45 /// Override destroyConstantImpl to make sure it doesn't get called on 46 /// GlobalValue's because they shouldn't be treated like other constants. 47 void GlobalValue::destroyConstantImpl() { 48 llvm_unreachable("You can't GV->destroyConstantImpl()!"); 49 } 50 51 Value *GlobalValue::handleOperandChangeImpl(Value *From, Value *To, Use *U) { 52 llvm_unreachable("Unsupported class for handleOperandChange()!"); 53 } 54 55 /// copyAttributesFrom - copy all additional attributes (those not needed to 56 /// create a GlobalValue) from the GlobalValue Src to this one. 57 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) { 58 setVisibility(Src->getVisibility()); 59 setUnnamedAddr(Src->hasUnnamedAddr()); 60 setDLLStorageClass(Src->getDLLStorageClass()); 61 } 62 63 unsigned GlobalValue::getAlignment() const { 64 if (auto *GA = dyn_cast<GlobalAlias>(this)) { 65 // In general we cannot compute this at the IR level, but we try. 66 if (const GlobalObject *GO = GA->getBaseObject()) 67 return GO->getAlignment(); 68 69 // FIXME: we should also be able to handle: 70 // Alias = Global + Offset 71 // Alias = Absolute 72 return 0; 73 } 74 return cast<GlobalObject>(this)->getAlignment(); 75 } 76 77 void GlobalObject::setAlignment(unsigned Align) { 78 assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!"); 79 assert(Align <= MaximumAlignment && 80 "Alignment is greater than MaximumAlignment!"); 81 unsigned AlignmentData = Log2_32(Align) + 1; 82 unsigned OldData = getGlobalValueSubClassData(); 83 setGlobalValueSubClassData((OldData & ~AlignmentMask) | AlignmentData); 84 assert(getAlignment() == Align && "Alignment representation error!"); 85 } 86 87 unsigned GlobalObject::getGlobalObjectSubClassData() const { 88 unsigned ValueData = getGlobalValueSubClassData(); 89 return ValueData >> AlignmentBits; 90 } 91 92 void GlobalObject::setGlobalObjectSubClassData(unsigned Val) { 93 unsigned OldData = getGlobalValueSubClassData(); 94 setGlobalValueSubClassData((OldData & AlignmentMask) | 95 (Val << AlignmentBits)); 96 assert(getGlobalObjectSubClassData() == Val && "representation error"); 97 } 98 99 void GlobalObject::copyAttributesFrom(const GlobalValue *Src) { 100 const auto *GV = cast<GlobalObject>(Src); 101 GlobalValue::copyAttributesFrom(GV); 102 setAlignment(GV->getAlignment()); 103 setSection(GV->getSection()); 104 } 105 106 const char *GlobalValue::getSection() const { 107 if (auto *GA = dyn_cast<GlobalAlias>(this)) { 108 // In general we cannot compute this at the IR level, but we try. 109 if (const GlobalObject *GO = GA->getBaseObject()) 110 return GO->getSection(); 111 return ""; 112 } 113 return cast<GlobalObject>(this)->getSection(); 114 } 115 116 Comdat *GlobalValue::getComdat() { 117 if (auto *GA = dyn_cast<GlobalAlias>(this)) { 118 // In general we cannot compute this at the IR level, but we try. 119 if (const GlobalObject *GO = GA->getBaseObject()) 120 return const_cast<GlobalObject *>(GO)->getComdat(); 121 return nullptr; 122 } 123 return cast<GlobalObject>(this)->getComdat(); 124 } 125 126 void GlobalObject::setSection(StringRef S) { Section = S; } 127 128 bool GlobalValue::isDeclaration() const { 129 // Globals are definitions if they have an initializer. 130 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this)) 131 return GV->getNumOperands() == 0; 132 133 // Functions are definitions if they have a body. 134 if (const Function *F = dyn_cast<Function>(this)) 135 return F->empty() && !F->isMaterializable(); 136 137 // Aliases are always definitions. 138 assert(isa<GlobalAlias>(this)); 139 return false; 140 } 141 142 //===----------------------------------------------------------------------===// 143 // GlobalVariable Implementation 144 //===----------------------------------------------------------------------===// 145 146 GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link, 147 Constant *InitVal, const Twine &Name, 148 ThreadLocalMode TLMode, unsigned AddressSpace, 149 bool isExternallyInitialized) 150 : GlobalObject(PointerType::get(Ty, AddressSpace), Value::GlobalVariableVal, 151 OperandTraits<GlobalVariable>::op_begin(this), 152 InitVal != nullptr, Link, Name), 153 isConstantGlobal(constant), 154 isExternallyInitializedConstant(isExternallyInitialized) { 155 setThreadLocalMode(TLMode); 156 if (InitVal) { 157 assert(InitVal->getType() == Ty && 158 "Initializer should be the same type as the GlobalVariable!"); 159 Op<0>() = InitVal; 160 } 161 } 162 163 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant, 164 LinkageTypes Link, Constant *InitVal, 165 const Twine &Name, GlobalVariable *Before, 166 ThreadLocalMode TLMode, unsigned AddressSpace, 167 bool isExternallyInitialized) 168 : GlobalObject(PointerType::get(Ty, AddressSpace), Value::GlobalVariableVal, 169 OperandTraits<GlobalVariable>::op_begin(this), 170 InitVal != nullptr, Link, Name), 171 isConstantGlobal(constant), 172 isExternallyInitializedConstant(isExternallyInitialized) { 173 setThreadLocalMode(TLMode); 174 if (InitVal) { 175 assert(InitVal->getType() == Ty && 176 "Initializer should be the same type as the GlobalVariable!"); 177 Op<0>() = InitVal; 178 } 179 180 if (Before) 181 Before->getParent()->getGlobalList().insert(Before, this); 182 else 183 M.getGlobalList().push_back(this); 184 } 185 186 void GlobalVariable::setParent(Module *parent) { 187 Parent = parent; 188 } 189 190 void GlobalVariable::removeFromParent() { 191 getParent()->getGlobalList().remove(this); 192 } 193 194 void GlobalVariable::eraseFromParent() { 195 getParent()->getGlobalList().erase(this); 196 } 197 198 void GlobalVariable::setInitializer(Constant *InitVal) { 199 if (!InitVal) { 200 if (hasInitializer()) { 201 // Note, the num operands is used to compute the offset of the operand, so 202 // the order here matters. Clearing the operand then clearing the num 203 // operands ensures we have the correct offset to the operand. 204 Op<0>().set(nullptr); 205 setGlobalVariableNumOperands(0); 206 } 207 } else { 208 assert(InitVal->getType() == getType()->getElementType() && 209 "Initializer type must match GlobalVariable type"); 210 // Note, the num operands is used to compute the offset of the operand, so 211 // the order here matters. We need to set num operands to 1 first so that 212 // we get the correct offset to the first operand when we set it. 213 if (!hasInitializer()) 214 setGlobalVariableNumOperands(1); 215 Op<0>().set(InitVal); 216 } 217 } 218 219 /// copyAttributesFrom - copy all additional attributes (those not needed to 220 /// create a GlobalVariable) from the GlobalVariable Src to this one. 221 void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) { 222 assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!"); 223 GlobalObject::copyAttributesFrom(Src); 224 const GlobalVariable *SrcVar = cast<GlobalVariable>(Src); 225 setThreadLocalMode(SrcVar->getThreadLocalMode()); 226 setExternallyInitialized(SrcVar->isExternallyInitialized()); 227 } 228 229 230 //===----------------------------------------------------------------------===// 231 // GlobalAlias Implementation 232 //===----------------------------------------------------------------------===// 233 234 GlobalAlias::GlobalAlias(PointerType *Ty, LinkageTypes Link, const Twine &Name, 235 Constant *Aliasee, Module *ParentModule) 236 : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) { 237 Op<0>() = Aliasee; 238 239 if (ParentModule) 240 ParentModule->getAliasList().push_back(this); 241 } 242 243 GlobalAlias *GlobalAlias::create(PointerType *Ty, LinkageTypes Link, 244 const Twine &Name, Constant *Aliasee, 245 Module *ParentModule) { 246 return new GlobalAlias(Ty, Link, Name, Aliasee, ParentModule); 247 } 248 249 GlobalAlias *GlobalAlias::create(PointerType *Ty, LinkageTypes Linkage, 250 const Twine &Name, Module *Parent) { 251 return create(Ty, Linkage, Name, nullptr, Parent); 252 } 253 254 GlobalAlias *GlobalAlias::create(PointerType *Ty, LinkageTypes Linkage, 255 const Twine &Name, GlobalValue *Aliasee) { 256 return create(Ty, Linkage, Name, Aliasee, Aliasee->getParent()); 257 } 258 259 GlobalAlias *GlobalAlias::create(LinkageTypes Link, const Twine &Name, 260 GlobalValue *Aliasee) { 261 PointerType *PTy = Aliasee->getType(); 262 return create(PTy, Link, Name, Aliasee); 263 } 264 265 GlobalAlias *GlobalAlias::create(const Twine &Name, GlobalValue *Aliasee) { 266 return create(Aliasee->getLinkage(), Name, Aliasee); 267 } 268 269 void GlobalAlias::setParent(Module *parent) { 270 Parent = parent; 271 } 272 273 void GlobalAlias::removeFromParent() { 274 getParent()->getAliasList().remove(this); 275 } 276 277 void GlobalAlias::eraseFromParent() { 278 getParent()->getAliasList().erase(this); 279 } 280 281 void GlobalAlias::setAliasee(Constant *Aliasee) { 282 assert((!Aliasee || Aliasee->getType() == getType()) && 283 "Alias and aliasee types should match!"); 284 setOperand(0, Aliasee); 285 } 286