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//===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file implements the GlobalValue & GlobalVariable classes for the IR
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//===----------------------------------------------------------------------===//
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#include "llvm/IR/GlobalValue.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/GlobalAlias.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/Support/ErrorHandling.h"
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//===----------------------------------------------------------------------===//
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//===----------------------------------------------------------------------===//
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bool GlobalValue::isMaterializable() const {
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if (const Function *F = dyn_cast<Function>(this))
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return F->isMaterializable();
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bool GlobalValue::isDematerializable() const {
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return getParent() && getParent()->isDematerializable(this);
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std::error_code GlobalValue::materialize() {
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return getParent()->materialize(this);
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void GlobalValue::dematerialize() {
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getParent()->dematerialize(this);
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/// Override destroyConstantImpl to make sure it doesn't get called on
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/// GlobalValue's because they shouldn't be treated like other constants.
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void GlobalValue::destroyConstantImpl() {
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llvm_unreachable("You can't GV->destroyConstantImpl()!");
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Value *GlobalValue::handleOperandChangeImpl(Value *From, Value *To, Use *U) {
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llvm_unreachable("Unsupported class for handleOperandChange()!");
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/// copyAttributesFrom - copy all additional attributes (those not needed to
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/// create a GlobalValue) from the GlobalValue Src to this one.
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void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
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setVisibility(Src->getVisibility());
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setUnnamedAddr(Src->hasUnnamedAddr());
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setDLLStorageClass(Src->getDLLStorageClass());
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unsigned GlobalValue::getAlignment() const {
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if (auto *GA = dyn_cast<GlobalAlias>(this)) {
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// In general we cannot compute this at the IR level, but we try.
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if (const GlobalObject *GO = GA->getBaseObject())
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return GO->getAlignment();
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// FIXME: we should also be able to handle:
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// Alias = Global + Offset
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return cast<GlobalObject>(this)->getAlignment();
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void GlobalObject::setAlignment(unsigned Align) {
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assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
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assert(Align <= MaximumAlignment &&
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"Alignment is greater than MaximumAlignment!");
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unsigned AlignmentData = Log2_32(Align) + 1;
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unsigned OldData = getGlobalValueSubClassData();
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setGlobalValueSubClassData((OldData & ~AlignmentMask) | AlignmentData);
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assert(getAlignment() == Align && "Alignment representation error!");
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unsigned GlobalObject::getGlobalObjectSubClassData() const {
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unsigned ValueData = getGlobalValueSubClassData();
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return ValueData >> AlignmentBits;
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void GlobalObject::setGlobalObjectSubClassData(unsigned Val) {
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unsigned OldData = getGlobalValueSubClassData();
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setGlobalValueSubClassData((OldData & AlignmentMask) |
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(Val << AlignmentBits));
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assert(getGlobalObjectSubClassData() == Val && "representation error");
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void GlobalObject::copyAttributesFrom(const GlobalValue *Src) {
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const auto *GV = cast<GlobalObject>(Src);
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GlobalValue::copyAttributesFrom(GV);
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setAlignment(GV->getAlignment());
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setSection(GV->getSection());
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const char *GlobalValue::getSection() const {
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if (auto *GA = dyn_cast<GlobalAlias>(this)) {
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// In general we cannot compute this at the IR level, but we try.
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if (const GlobalObject *GO = GA->getBaseObject())
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return GO->getSection();
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return cast<GlobalObject>(this)->getSection();
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Comdat *GlobalValue::getComdat() {
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if (auto *GA = dyn_cast<GlobalAlias>(this)) {
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// In general we cannot compute this at the IR level, but we try.
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if (const GlobalObject *GO = GA->getBaseObject())
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return const_cast<GlobalObject *>(GO)->getComdat();
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return cast<GlobalObject>(this)->getComdat();
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void GlobalObject::setSection(StringRef S) { Section = S; }
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bool GlobalValue::isDeclaration() const {
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// Globals are definitions if they have an initializer.
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if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
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return GV->getNumOperands() == 0;
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// Functions are definitions if they have a body.
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if (const Function *F = dyn_cast<Function>(this))
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return F->empty() && !F->isMaterializable();
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// Aliases are always definitions.
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assert(isa<GlobalAlias>(this));
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//===----------------------------------------------------------------------===//
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// GlobalVariable Implementation
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//===----------------------------------------------------------------------===//
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GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
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Constant *InitVal, const Twine &Name,
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ThreadLocalMode TLMode, unsigned AddressSpace,
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bool isExternallyInitialized)
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: GlobalObject(PointerType::get(Ty, AddressSpace), Value::GlobalVariableVal,
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OperandTraits<GlobalVariable>::op_begin(this),
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InitVal != nullptr, Link, Name),
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isConstantGlobal(constant),
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isExternallyInitializedConstant(isExternallyInitialized) {
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setThreadLocalMode(TLMode);
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assert(InitVal->getType() == Ty &&
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"Initializer should be the same type as the GlobalVariable!");
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GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
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LinkageTypes Link, Constant *InitVal,
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const Twine &Name, GlobalVariable *Before,
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ThreadLocalMode TLMode, unsigned AddressSpace,
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bool isExternallyInitialized)
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: GlobalObject(PointerType::get(Ty, AddressSpace), Value::GlobalVariableVal,
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OperandTraits<GlobalVariable>::op_begin(this),
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InitVal != nullptr, Link, Name),
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isConstantGlobal(constant),
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isExternallyInitializedConstant(isExternallyInitialized) {
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setThreadLocalMode(TLMode);
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assert(InitVal->getType() == Ty &&
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"Initializer should be the same type as the GlobalVariable!");
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Before->getParent()->getGlobalList().insert(Before, this);
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M.getGlobalList().push_back(this);
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void GlobalVariable::setParent(Module *parent) {
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void GlobalVariable::removeFromParent() {
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getParent()->getGlobalList().remove(this);
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void GlobalVariable::eraseFromParent() {
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getParent()->getGlobalList().erase(this);
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void GlobalVariable::setInitializer(Constant *InitVal) {
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if (hasInitializer()) {
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// Note, the num operands is used to compute the offset of the operand, so
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// the order here matters. Clearing the operand then clearing the num
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// operands ensures we have the correct offset to the operand.
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Op<0>().set(nullptr);
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setGlobalVariableNumOperands(0);
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assert(InitVal->getType() == getType()->getElementType() &&
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"Initializer type must match GlobalVariable type");
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// Note, the num operands is used to compute the offset of the operand, so
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// the order here matters. We need to set num operands to 1 first so that
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// we get the correct offset to the first operand when we set it.
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if (!hasInitializer())
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setGlobalVariableNumOperands(1);
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Op<0>().set(InitVal);
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/// copyAttributesFrom - copy all additional attributes (those not needed to
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/// create a GlobalVariable) from the GlobalVariable Src to this one.
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void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
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assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!");
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GlobalObject::copyAttributesFrom(Src);
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const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
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setThreadLocalMode(SrcVar->getThreadLocalMode());
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setExternallyInitialized(SrcVar->isExternallyInitialized());
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//===----------------------------------------------------------------------===//
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// GlobalAlias Implementation
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//===----------------------------------------------------------------------===//
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GlobalAlias::GlobalAlias(PointerType *Ty, LinkageTypes Link, const Twine &Name,
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Constant *Aliasee, Module *ParentModule)
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: GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) {
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ParentModule->getAliasList().push_back(this);
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GlobalAlias *GlobalAlias::create(PointerType *Ty, LinkageTypes Link,
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const Twine &Name, Constant *Aliasee,
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Module *ParentModule) {
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return new GlobalAlias(Ty, Link, Name, Aliasee, ParentModule);
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GlobalAlias *GlobalAlias::create(PointerType *Ty, LinkageTypes Linkage,
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const Twine &Name, Module *Parent) {
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return create(Ty, Linkage, Name, nullptr, Parent);
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GlobalAlias *GlobalAlias::create(PointerType *Ty, LinkageTypes Linkage,
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const Twine &Name, GlobalValue *Aliasee) {
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return create(Ty, Linkage, Name, Aliasee, Aliasee->getParent());
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GlobalAlias *GlobalAlias::create(LinkageTypes Link, const Twine &Name,
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GlobalValue *Aliasee) {
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PointerType *PTy = Aliasee->getType();
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return create(PTy, Link, Name, Aliasee);
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GlobalAlias *GlobalAlias::create(const Twine &Name, GlobalValue *Aliasee) {
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return create(Aliasee->getLinkage(), Name, Aliasee);
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void GlobalAlias::setParent(Module *parent) {
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void GlobalAlias::removeFromParent() {
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getParent()->getAliasList().remove(this);
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void GlobalAlias::eraseFromParent() {
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getParent()->getAliasList().erase(this);
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void GlobalAlias::setAliasee(Constant *Aliasee) {
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assert((!Aliasee || Aliasee->getType() == getType()) &&
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"Alias and aliasee types should match!");
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setOperand(0, Aliasee);