forked from OSchip/llvm-project
277 lines
9.0 KiB
C++
277 lines
9.0 KiB
C++
//===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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//
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// This file implements the GlobalValue & GlobalVariable classes for the VMCore
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// library.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Constants.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/GlobalAlias.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Module.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/LeakDetector.h"
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// GlobalValue Class
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//===----------------------------------------------------------------------===//
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/// removeDeadUsersOfConstant - If the specified constantexpr is dead, remove
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/// it. This involves recursively eliminating any dead users of the
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/// constantexpr.
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static bool removeDeadUsersOfConstant(const Constant *C) {
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if (isa<GlobalValue>(C)) return false; // Cannot remove this
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while (!C->use_empty()) {
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const Constant *User = dyn_cast<Constant>(C->use_back());
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if (!User) return false; // Non-constant usage;
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if (!removeDeadUsersOfConstant(User))
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return false; // Constant wasn't dead
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}
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const_cast<Constant*>(C)->destroyConstant();
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return true;
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}
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/// removeDeadConstantUsers - If there are any dead constant users dangling
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/// off of this global value, remove them. This method is useful for clients
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/// that want to check to see if a global is unused, but don't want to deal
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/// with potentially dead constants hanging off of the globals.
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void GlobalValue::removeDeadConstantUsers() const {
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Value::use_const_iterator I = use_begin(), E = use_end();
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Value::use_const_iterator LastNonDeadUser = E;
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while (I != E) {
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if (const Constant *User = dyn_cast<Constant>(*I)) {
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if (!removeDeadUsersOfConstant(User)) {
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// If the constant wasn't dead, remember that this was the last live use
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// and move on to the next constant.
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LastNonDeadUser = I;
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++I;
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} else {
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// If the constant was dead, then the iterator is invalidated.
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if (LastNonDeadUser == E) {
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I = use_begin();
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if (I == E) break;
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} else {
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I = LastNonDeadUser;
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++I;
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}
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}
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} else {
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LastNonDeadUser = I;
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++I;
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}
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}
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}
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/// Override destroyConstant 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::destroyConstant() {
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llvm_unreachable("You can't GV->destroyConstant()!");
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}
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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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setAlignment(Src->getAlignment());
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setSection(Src->getSection());
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setVisibility(Src->getVisibility());
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}
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//===----------------------------------------------------------------------===//
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// GlobalVariable Implementation
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//===----------------------------------------------------------------------===//
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GlobalVariable::GlobalVariable(LLVMContext &Context, const Type *Ty,
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bool constant, LinkageTypes Link,
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Constant *InitVal, const Twine &Name,
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bool ThreadLocal, unsigned AddressSpace)
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: GlobalValue(PointerType::get(Ty, AddressSpace),
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Value::GlobalVariableVal,
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OperandTraits<GlobalVariable>::op_begin(this),
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InitVal != 0, Link, Name),
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isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
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if (InitVal) {
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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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Op<0>() = InitVal;
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}
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LeakDetector::addGarbageObject(this);
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}
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GlobalVariable::GlobalVariable(Module &M, const Type *Ty, bool constant,
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LinkageTypes Link, Constant *InitVal,
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const Twine &Name,
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GlobalVariable *Before, bool ThreadLocal,
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unsigned AddressSpace)
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: GlobalValue(PointerType::get(Ty, AddressSpace),
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Value::GlobalVariableVal,
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OperandTraits<GlobalVariable>::op_begin(this),
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InitVal != 0, Link, Name),
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isConstantGlobal(constant), isThreadLocalSymbol(ThreadLocal) {
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if (InitVal) {
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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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Op<0>() = InitVal;
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}
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LeakDetector::addGarbageObject(this);
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if (Before)
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Before->getParent()->getGlobalList().insert(Before, this);
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else
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M.getGlobalList().push_back(this);
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}
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void GlobalVariable::setParent(Module *parent) {
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if (getParent())
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LeakDetector::addGarbageObject(this);
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Parent = parent;
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if (getParent())
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LeakDetector::removeGarbageObject(this);
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}
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void GlobalVariable::removeFromParent() {
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getParent()->getGlobalList().remove(this);
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}
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void GlobalVariable::eraseFromParent() {
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getParent()->getGlobalList().erase(this);
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}
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void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
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Use *U) {
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// If you call this, then you better know this GVar has a constant
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// initializer worth replacing. Enforce that here.
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assert(getNumOperands() == 1 &&
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"Attempt to replace uses of Constants on a GVar with no initializer");
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// And, since you know it has an initializer, the From value better be
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// the initializer :)
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assert(getOperand(0) == From &&
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"Attempt to replace wrong constant initializer in GVar");
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// And, you better have a constant for the replacement value
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assert(isa<Constant>(To) &&
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"Attempt to replace GVar initializer with non-constant");
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// Okay, preconditions out of the way, replace the constant initializer.
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this->setOperand(0, cast<Constant>(To));
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}
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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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GlobalValue::copyAttributesFrom(Src);
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const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
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setThreadLocal(SrcVar->isThreadLocal());
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}
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//===----------------------------------------------------------------------===//
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// GlobalAlias Implementation
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//===----------------------------------------------------------------------===//
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GlobalAlias::GlobalAlias(const Type *Ty, LinkageTypes Link,
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const Twine &Name, Constant* aliasee,
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Module *ParentModule)
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: GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) {
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LeakDetector::addGarbageObject(this);
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if (aliasee)
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assert(aliasee->getType() == Ty && "Alias and aliasee types should match!");
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Op<0>() = aliasee;
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if (ParentModule)
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ParentModule->getAliasList().push_back(this);
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}
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void GlobalAlias::setParent(Module *parent) {
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if (getParent())
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LeakDetector::addGarbageObject(this);
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Parent = parent;
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if (getParent())
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LeakDetector::removeGarbageObject(this);
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}
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void GlobalAlias::removeFromParent() {
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getParent()->getAliasList().remove(this);
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}
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void GlobalAlias::eraseFromParent() {
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getParent()->getAliasList().erase(this);
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}
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bool GlobalAlias::isDeclaration() const {
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const GlobalValue* AV = getAliasedGlobal();
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if (AV)
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return AV->isDeclaration();
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else
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return false;
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}
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void GlobalAlias::setAliasee(Constant *Aliasee)
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{
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if (Aliasee)
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assert(Aliasee->getType() == getType() &&
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"Alias and aliasee types should match!");
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setOperand(0, Aliasee);
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}
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const GlobalValue *GlobalAlias::getAliasedGlobal() const {
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const Constant *C = getAliasee();
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if (C) {
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if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
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return GV;
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else {
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const ConstantExpr *CE = 0;
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if ((CE = dyn_cast<ConstantExpr>(C)) &&
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(CE->getOpcode() == Instruction::BitCast ||
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CE->getOpcode() == Instruction::GetElementPtr))
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return dyn_cast<GlobalValue>(CE->getOperand(0));
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else
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llvm_unreachable("Unsupported aliasee");
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}
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}
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return 0;
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}
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const GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) const {
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SmallPtrSet<const GlobalValue*, 3> Visited;
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// Check if we need to stop early.
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if (stopOnWeak && mayBeOverridden())
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return this;
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const GlobalValue *GV = getAliasedGlobal();
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Visited.insert(GV);
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// Iterate over aliasing chain, stopping on weak alias if necessary.
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while (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV)) {
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if (stopOnWeak && GA->mayBeOverridden())
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break;
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GV = GA->getAliasedGlobal();
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if (!Visited.insert(GV))
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return NULL;
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}
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return GV;
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}
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