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 30 bool GlobalValue::isMaterializable() const { 31 return getParent() && getParent()->isMaterializable(this); 32 } 33 bool GlobalValue::isDematerializable() const { 34 return getParent() && getParent()->isDematerializable(this); 35 } 36 bool GlobalValue::Materialize(std::string *ErrInfo) { 37 return getParent()->Materialize(this, ErrInfo); 38 } 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. 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. 51 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) { 52 setAlignment(Src->getAlignment()); 53 setSection(Src->getSection()); 54 setVisibility(Src->getVisibility()); 55 setUnnamedAddr(Src->hasUnnamedAddr()); 56 setDLLStorageClass(Src->getDLLStorageClass()); 57 } 58 59 void GlobalValue::setAlignment(unsigned Align) { 60 assert((!isa<GlobalAlias>(this) || !Align) && 61 "GlobalAlias should not have an alignment!"); 62 assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!"); 63 assert(Align <= MaximumAlignment && 64 "Alignment is greater than MaximumAlignment!"); 65 Alignment = Log2_32(Align) + 1; 66 assert(getAlignment() == Align && "Alignment representation error!"); 67 } 68 69 bool GlobalValue::isDeclaration() const { 70 // Globals are definitions if they have an initializer. 71 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this)) 72 return GV->getNumOperands() == 0; 73 74 // Functions are definitions if they have a body. 75 if (const Function *F = dyn_cast<Function>(this)) 76 return F->empty(); 77 78 // Aliases are always definitions. 79 assert(isa<GlobalAlias>(this)); 80 return false; 81 } 82 83 //===----------------------------------------------------------------------===// 84 // GlobalVariable Implementation 85 //===----------------------------------------------------------------------===// 86 87 GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link, 88 Constant *InitVal, 89 const Twine &Name, ThreadLocalMode TLMode, 90 unsigned AddressSpace, 91 bool isExternallyInitialized) 92 : GlobalValue(PointerType::get(Ty, AddressSpace), 93 Value::GlobalVariableVal, 94 OperandTraits<GlobalVariable>::op_begin(this), 95 InitVal != 0, Link, Name), 96 isConstantGlobal(constant), threadLocalMode(TLMode), 97 isExternallyInitializedConstant(isExternallyInitialized) { 98 if (InitVal) { 99 assert(InitVal->getType() == Ty && 100 "Initializer should be the same type as the GlobalVariable!"); 101 Op<0>() = InitVal; 102 } 103 104 LeakDetector::addGarbageObject(this); 105 } 106 107 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant, 108 LinkageTypes Link, Constant *InitVal, 109 const Twine &Name, 110 GlobalVariable *Before, ThreadLocalMode TLMode, 111 unsigned AddressSpace, 112 bool isExternallyInitialized) 113 : GlobalValue(PointerType::get(Ty, AddressSpace), 114 Value::GlobalVariableVal, 115 OperandTraits<GlobalVariable>::op_begin(this), 116 InitVal != 0, Link, Name), 117 isConstantGlobal(constant), threadLocalMode(TLMode), 118 isExternallyInitializedConstant(isExternallyInitialized) { 119 if (InitVal) { 120 assert(InitVal->getType() == Ty && 121 "Initializer should be the same type as the GlobalVariable!"); 122 Op<0>() = InitVal; 123 } 124 125 LeakDetector::addGarbageObject(this); 126 127 if (Before) 128 Before->getParent()->getGlobalList().insert(Before, this); 129 else 130 M.getGlobalList().push_back(this); 131 } 132 133 void GlobalVariable::setParent(Module *parent) { 134 if (getParent()) 135 LeakDetector::addGarbageObject(this); 136 Parent = parent; 137 if (getParent()) 138 LeakDetector::removeGarbageObject(this); 139 } 140 141 void GlobalVariable::removeFromParent() { 142 getParent()->getGlobalList().remove(this); 143 } 144 145 void GlobalVariable::eraseFromParent() { 146 getParent()->getGlobalList().erase(this); 147 } 148 149 void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To, 150 Use *U) { 151 // If you call this, then you better know this GVar has a constant 152 // initializer worth replacing. Enforce that here. 153 assert(getNumOperands() == 1 && 154 "Attempt to replace uses of Constants on a GVar with no initializer"); 155 156 // And, since you know it has an initializer, the From value better be 157 // the initializer :) 158 assert(getOperand(0) == From && 159 "Attempt to replace wrong constant initializer in GVar"); 160 161 // And, you better have a constant for the replacement value 162 assert(isa<Constant>(To) && 163 "Attempt to replace GVar initializer with non-constant"); 164 165 // Okay, preconditions out of the way, replace the constant initializer. 166 this->setOperand(0, cast<Constant>(To)); 167 } 168 169 void GlobalVariable::setInitializer(Constant *InitVal) { 170 if (InitVal == 0) { 171 if (hasInitializer()) { 172 Op<0>().set(0); 173 NumOperands = 0; 174 } 175 } else { 176 assert(InitVal->getType() == getType()->getElementType() && 177 "Initializer type must match GlobalVariable type"); 178 if (!hasInitializer()) 179 NumOperands = 1; 180 Op<0>().set(InitVal); 181 } 182 } 183 184 /// copyAttributesFrom - copy all additional attributes (those not needed to 185 /// create a GlobalVariable) from the GlobalVariable Src to this one. 186 void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) { 187 assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!"); 188 GlobalValue::copyAttributesFrom(Src); 189 const GlobalVariable *SrcVar = cast<GlobalVariable>(Src); 190 setThreadLocalMode(SrcVar->getThreadLocalMode()); 191 } 192 193 194 //===----------------------------------------------------------------------===// 195 // GlobalAlias Implementation 196 //===----------------------------------------------------------------------===// 197 198 GlobalAlias::GlobalAlias(Type *Ty, LinkageTypes Link, 199 const Twine &Name, Constant* aliasee, 200 Module *ParentModule) 201 : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) { 202 LeakDetector::addGarbageObject(this); 203 204 if (aliasee) 205 assert(aliasee->getType() == Ty && "Alias and aliasee types should match!"); 206 Op<0>() = aliasee; 207 208 if (ParentModule) 209 ParentModule->getAliasList().push_back(this); 210 } 211 212 void GlobalAlias::setParent(Module *parent) { 213 if (getParent()) 214 LeakDetector::addGarbageObject(this); 215 Parent = parent; 216 if (getParent()) 217 LeakDetector::removeGarbageObject(this); 218 } 219 220 void GlobalAlias::removeFromParent() { 221 getParent()->getAliasList().remove(this); 222 } 223 224 void GlobalAlias::eraseFromParent() { 225 getParent()->getAliasList().erase(this); 226 } 227 228 void GlobalAlias::setAliasee(Constant *Aliasee) { 229 assert((!Aliasee || Aliasee->getType() == getType()) && 230 "Alias and aliasee types should match!"); 231 232 setOperand(0, Aliasee); 233 } 234 235 GlobalValue *GlobalAlias::getAliasedGlobal() { 236 Constant *C = getAliasee(); 237 if (C == 0) return 0; 238 239 if (GlobalValue *GV = dyn_cast<GlobalValue>(C)) 240 return GV; 241 242 ConstantExpr *CE = cast<ConstantExpr>(C); 243 assert((CE->getOpcode() == Instruction::BitCast || 244 CE->getOpcode() == Instruction::AddrSpaceCast || 245 CE->getOpcode() == Instruction::GetElementPtr) && 246 "Unsupported aliasee"); 247 248 return cast<GlobalValue>(CE->getOperand(0)); 249 } 250 251 GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) { 252 SmallPtrSet<GlobalValue*, 3> Visited; 253 254 // Check if we need to stop early. 255 if (stopOnWeak && mayBeOverridden()) 256 return this; 257 258 GlobalValue *GV = getAliasedGlobal(); 259 Visited.insert(GV); 260 261 // Iterate over aliasing chain, stopping on weak alias if necessary. 262 while (GlobalAlias *GA = dyn_cast<GlobalAlias>(GV)) { 263 if (stopOnWeak && GA->mayBeOverridden()) 264 break; 265 266 GV = GA->getAliasedGlobal(); 267 268 if (!Visited.insert(GV)) 269 return 0; 270 } 271 272 return GV; 273 } 274