| //===-- Value.cpp - Implement the Value class -----------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the Value, ValueHandle, and User classes. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/IR/Value.h" |
| #include "LLVMContextImpl.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/IR/Constant.h" |
| #include "llvm/IR/Constants.h" |
| #include "llvm/IR/DerivedTypes.h" |
| #include "llvm/IR/InstrTypes.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IR/Operator.h" |
| #include "llvm/IR/ValueSymbolTable.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/GetElementPtrTypeIterator.h" |
| #include "llvm/Support/LeakDetector.h" |
| #include "llvm/Support/ManagedStatic.h" |
| #include "llvm/Support/ValueHandle.h" |
| #include <algorithm> |
| using namespace llvm; |
| |
| //===----------------------------------------------------------------------===// |
| // Value Class |
| //===----------------------------------------------------------------------===// |
| |
| static inline Type *checkType(Type *Ty) { |
| assert(Ty && "Value defined with a null type: Error!"); |
| return const_cast<Type*>(Ty); |
| } |
| |
| Value::Value(Type *ty, unsigned scid) |
| : SubclassID(scid), HasValueHandle(0), |
| SubclassOptionalData(0), SubclassData(0), VTy((Type*)checkType(ty)), |
| UseList(0), Name(0) { |
| // FIXME: Why isn't this in the subclass gunk?? |
| // Note, we cannot call isa<CallInst> before the CallInst has been |
| // constructed. |
| if (SubclassID == Instruction::Call || SubclassID == Instruction::Invoke) |
| assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) && |
| "invalid CallInst type!"); |
| else if (SubclassID != BasicBlockVal && |
| (SubclassID < ConstantFirstVal || SubclassID > ConstantLastVal)) |
| assert((VTy->isFirstClassType() || VTy->isVoidTy()) && |
| "Cannot create non-first-class values except for constants!"); |
| } |
| |
| Value::~Value() { |
| // Notify all ValueHandles (if present) that this value is going away. |
| if (HasValueHandle) |
| ValueHandleBase::ValueIsDeleted(this); |
| |
| #ifndef NDEBUG // Only in -g mode... |
| // Check to make sure that there are no uses of this value that are still |
| // around when the value is destroyed. If there are, then we have a dangling |
| // reference and something is wrong. This code is here to print out what is |
| // still being referenced. The value in question should be printed as |
| // a <badref> |
| // |
| if (!use_empty()) { |
| dbgs() << "While deleting: " << *VTy << " %" << getName() << "\n"; |
| for (use_iterator I = use_begin(), E = use_end(); I != E; ++I) |
| dbgs() << "Use still stuck around after Def is destroyed:" |
| << **I << "\n"; |
| } |
| #endif |
| assert(use_empty() && "Uses remain when a value is destroyed!"); |
| |
| // If this value is named, destroy the name. This should not be in a symtab |
| // at this point. |
| if (Name && SubclassID != MDStringVal) |
| Name->Destroy(); |
| |
| // There should be no uses of this object anymore, remove it. |
| LeakDetector::removeGarbageObject(this); |
| } |
| |
| /// hasNUses - Return true if this Value has exactly N users. |
| /// |
| bool Value::hasNUses(unsigned N) const { |
| const_use_iterator UI = use_begin(), E = use_end(); |
| |
| for (; N; --N, ++UI) |
| if (UI == E) return false; // Too few. |
| return UI == E; |
| } |
| |
| /// hasNUsesOrMore - Return true if this value has N users or more. This is |
| /// logically equivalent to getNumUses() >= N. |
| /// |
| bool Value::hasNUsesOrMore(unsigned N) const { |
| const_use_iterator UI = use_begin(), E = use_end(); |
| |
| for (; N; --N, ++UI) |
| if (UI == E) return false; // Too few. |
| |
| return true; |
| } |
| |
| /// isUsedInBasicBlock - Return true if this value is used in the specified |
| /// basic block. |
| bool Value::isUsedInBasicBlock(const BasicBlock *BB) const { |
| // Start by scanning over the instructions looking for a use before we start |
| // the expensive use iteration. |
| unsigned MaxBlockSize = 3; |
| for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) { |
| if (std::find(I->op_begin(), I->op_end(), this) != I->op_end()) |
| return true; |
| if (MaxBlockSize-- == 0) // If the block is larger fall back to use_iterator |
| break; |
| } |
| |
| if (MaxBlockSize != 0) // We scanned the entire block and found no use. |
| return false; |
| |
| for (const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) { |
| const Instruction *User = dyn_cast<Instruction>(*I); |
| if (User && User->getParent() == BB) |
| return true; |
| } |
| return false; |
| } |
| |
| |
| /// getNumUses - This method computes the number of uses of this Value. This |
| /// is a linear time operation. Use hasOneUse or hasNUses to check for specific |
| /// values. |
| unsigned Value::getNumUses() const { |
| return (unsigned)std::distance(use_begin(), use_end()); |
| } |
| |
| static bool getSymTab(Value *V, ValueSymbolTable *&ST) { |
| ST = 0; |
| if (Instruction *I = dyn_cast<Instruction>(V)) { |
| if (BasicBlock *P = I->getParent()) |
| if (Function *PP = P->getParent()) |
| ST = &PP->getValueSymbolTable(); |
| } else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) { |
| if (Function *P = BB->getParent()) |
| ST = &P->getValueSymbolTable(); |
| } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { |
| if (Module *P = GV->getParent()) |
| ST = &P->getValueSymbolTable(); |
| } else if (Argument *A = dyn_cast<Argument>(V)) { |
| if (Function *P = A->getParent()) |
| ST = &P->getValueSymbolTable(); |
| } else if (isa<MDString>(V)) |
| return true; |
| else { |
| assert(isa<Constant>(V) && "Unknown value type!"); |
| return true; // no name is setable for this. |
| } |
| return false; |
| } |
| |
| StringRef Value::getName() const { |
| // Make sure the empty string is still a C string. For historical reasons, |
| // some clients want to call .data() on the result and expect it to be null |
| // terminated. |
| if (!Name) return StringRef("", 0); |
| return Name->getKey(); |
| } |
| |
| void Value::setName(const Twine &NewName) { |
| assert(SubclassID != MDStringVal && |
| "Cannot set the name of MDString with this method!"); |
| |
| // Fast path for common IRBuilder case of setName("") when there is no name. |
| if (NewName.isTriviallyEmpty() && !hasName()) |
| return; |
| |
| SmallString<256> NameData; |
| StringRef NameRef = NewName.toStringRef(NameData); |
| |
| // Name isn't changing? |
| if (getName() == NameRef) |
| return; |
| |
| assert(!getType()->isVoidTy() && "Cannot assign a name to void values!"); |
| |
| // Get the symbol table to update for this object. |
| ValueSymbolTable *ST; |
| if (getSymTab(this, ST)) |
| return; // Cannot set a name on this value (e.g. constant). |
| |
| if (!ST) { // No symbol table to update? Just do the change. |
| if (NameRef.empty()) { |
| // Free the name for this value. |
| Name->Destroy(); |
| Name = 0; |
| return; |
| } |
| |
| if (Name) |
| Name->Destroy(); |
| |
| // NOTE: Could optimize for the case the name is shrinking to not deallocate |
| // then reallocated. |
| |
| // Create the new name. |
| Name = ValueName::Create(NameRef.begin(), NameRef.end()); |
| Name->setValue(this); |
| return; |
| } |
| |
| // NOTE: Could optimize for the case the name is shrinking to not deallocate |
| // then reallocated. |
| if (hasName()) { |
| // Remove old name. |
| ST->removeValueName(Name); |
| Name->Destroy(); |
| Name = 0; |
| |
| if (NameRef.empty()) |
| return; |
| } |
| |
| // Name is changing to something new. |
| Name = ST->createValueName(NameRef, this); |
| } |
| |
| |
| /// takeName - transfer the name from V to this value, setting V's name to |
| /// empty. It is an error to call V->takeName(V). |
| void Value::takeName(Value *V) { |
| assert(SubclassID != MDStringVal && "Cannot take the name of an MDString!"); |
| |
| ValueSymbolTable *ST = 0; |
| // If this value has a name, drop it. |
| if (hasName()) { |
| // Get the symtab this is in. |
| if (getSymTab(this, ST)) { |
| // We can't set a name on this value, but we need to clear V's name if |
| // it has one. |
| if (V->hasName()) V->setName(""); |
| return; // Cannot set a name on this value (e.g. constant). |
| } |
| |
| // Remove old name. |
| if (ST) |
| ST->removeValueName(Name); |
| Name->Destroy(); |
| Name = 0; |
| } |
| |
| // Now we know that this has no name. |
| |
| // If V has no name either, we're done. |
| if (!V->hasName()) return; |
| |
| // Get this's symtab if we didn't before. |
| if (!ST) { |
| if (getSymTab(this, ST)) { |
| // Clear V's name. |
| V->setName(""); |
| return; // Cannot set a name on this value (e.g. constant). |
| } |
| } |
| |
| // Get V's ST, this should always succed, because V has a name. |
| ValueSymbolTable *VST; |
| bool Failure = getSymTab(V, VST); |
| assert(!Failure && "V has a name, so it should have a ST!"); (void)Failure; |
| |
| // If these values are both in the same symtab, we can do this very fast. |
| // This works even if both values have no symtab yet. |
| if (ST == VST) { |
| // Take the name! |
| Name = V->Name; |
| V->Name = 0; |
| Name->setValue(this); |
| return; |
| } |
| |
| // Otherwise, things are slightly more complex. Remove V's name from VST and |
| // then reinsert it into ST. |
| |
| if (VST) |
| VST->removeValueName(V->Name); |
| Name = V->Name; |
| V->Name = 0; |
| Name->setValue(this); |
| |
| if (ST) |
| ST->reinsertValue(this); |
| } |
| |
| |
| void Value::replaceAllUsesWith(Value *New) { |
| assert(New && "Value::replaceAllUsesWith(<null>) is invalid!"); |
| assert(New != this && "this->replaceAllUsesWith(this) is NOT valid!"); |
| assert(New->getType() == getType() && |
| "replaceAllUses of value with new value of different type!"); |
| |
| // Notify all ValueHandles (if present) that this value is going away. |
| if (HasValueHandle) |
| ValueHandleBase::ValueIsRAUWd(this, New); |
| |
| while (!use_empty()) { |
| Use &U = *UseList; |
| // Must handle Constants specially, we cannot call replaceUsesOfWith on a |
| // constant because they are uniqued. |
| if (Constant *C = dyn_cast<Constant>(U.getUser())) { |
| if (!isa<GlobalValue>(C)) { |
| C->replaceUsesOfWithOnConstant(this, New, &U); |
| continue; |
| } |
| } |
| |
| U.set(New); |
| } |
| |
| if (BasicBlock *BB = dyn_cast<BasicBlock>(this)) |
| BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New)); |
| } |
| |
| namespace { |
| // Various metrics for how much to strip off of pointers. |
| enum PointerStripKind { |
| PSK_ZeroIndices, |
| PSK_InBoundsConstantIndices, |
| PSK_InBounds |
| }; |
| |
| template <PointerStripKind StripKind> |
| static Value *stripPointerCastsAndOffsets(Value *V) { |
| if (!V->getType()->isPointerTy()) |
| return V; |
| |
| // Even though we don't look through PHI nodes, we could be called on an |
| // instruction in an unreachable block, which may be on a cycle. |
| SmallPtrSet<Value *, 4> Visited; |
| |
| Visited.insert(V); |
| do { |
| if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { |
| switch (StripKind) { |
| case PSK_ZeroIndices: |
| if (!GEP->hasAllZeroIndices()) |
| return V; |
| break; |
| case PSK_InBoundsConstantIndices: |
| if (!GEP->hasAllConstantIndices()) |
| return V; |
| // fallthrough |
| case PSK_InBounds: |
| if (!GEP->isInBounds()) |
| return V; |
| break; |
| } |
| V = GEP->getPointerOperand(); |
| } else if (Operator::getOpcode(V) == Instruction::BitCast) { |
| V = cast<Operator>(V)->getOperand(0); |
| } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) { |
| if (GA->mayBeOverridden()) |
| return V; |
| V = GA->getAliasee(); |
| } else { |
| return V; |
| } |
| assert(V->getType()->isPointerTy() && "Unexpected operand type!"); |
| } while (Visited.insert(V)); |
| |
| return V; |
| } |
| } // namespace |
| |
| Value *Value::stripPointerCasts() { |
| return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this); |
| } |
| |
| Value *Value::stripInBoundsConstantOffsets() { |
| return stripPointerCastsAndOffsets<PSK_InBoundsConstantIndices>(this); |
| } |
| |
| Value *Value::stripInBoundsOffsets() { |
| return stripPointerCastsAndOffsets<PSK_InBounds>(this); |
| } |
| |
| /// isDereferenceablePointer - Test if this value is always a pointer to |
| /// allocated and suitably aligned memory for a simple load or store. |
| static bool isDereferenceablePointer(const Value *V, |
| SmallPtrSet<const Value *, 32> &Visited) { |
| // Note that it is not safe to speculate into a malloc'd region because |
| // malloc may return null. |
| // It's also not always safe to follow a bitcast, for example: |
| // bitcast i8* (alloca i8) to i32* |
| // would result in a 4-byte load from a 1-byte alloca. Some cases could |
| // be handled using DataLayout to check sizes and alignments though. |
| |
| // These are obviously ok. |
| if (isa<AllocaInst>(V)) return true; |
| |
| // Global variables which can't collapse to null are ok. |
| if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) |
| return !GV->hasExternalWeakLinkage(); |
| |
| // byval arguments are ok. |
| if (const Argument *A = dyn_cast<Argument>(V)) |
| return A->hasByValAttr(); |
| |
| // For GEPs, determine if the indexing lands within the allocated object. |
| if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { |
| // Conservatively require that the base pointer be fully dereferenceable. |
| if (!Visited.insert(GEP->getOperand(0))) |
| return false; |
| if (!isDereferenceablePointer(GEP->getOperand(0), Visited)) |
| return false; |
| // Check the indices. |
| gep_type_iterator GTI = gep_type_begin(GEP); |
| for (User::const_op_iterator I = GEP->op_begin()+1, |
| E = GEP->op_end(); I != E; ++I) { |
| Value *Index = *I; |
| Type *Ty = *GTI++; |
| // Struct indices can't be out of bounds. |
| if (isa<StructType>(Ty)) |
| continue; |
| ConstantInt *CI = dyn_cast<ConstantInt>(Index); |
| if (!CI) |
| return false; |
| // Zero is always ok. |
| if (CI->isZero()) |
| continue; |
| // Check to see that it's within the bounds of an array. |
| ArrayType *ATy = dyn_cast<ArrayType>(Ty); |
| if (!ATy) |
| return false; |
| if (CI->getValue().getActiveBits() > 64) |
| return false; |
| if (CI->getZExtValue() >= ATy->getNumElements()) |
| return false; |
| } |
| // Indices check out; this is dereferenceable. |
| return true; |
| } |
| |
| // If we don't know, assume the worst. |
| return false; |
| } |
| |
| /// isDereferenceablePointer - Test if this value is always a pointer to |
| /// allocated and suitably aligned memory for a simple load or store. |
| bool Value::isDereferenceablePointer() const { |
| SmallPtrSet<const Value *, 32> Visited; |
| return ::isDereferenceablePointer(this, Visited); |
| } |
| |
| /// DoPHITranslation - If this value is a PHI node with CurBB as its parent, |
| /// return the value in the PHI node corresponding to PredBB. If not, return |
| /// ourself. This is useful if you want to know the value something has in a |
| /// predecessor block. |
| Value *Value::DoPHITranslation(const BasicBlock *CurBB, |
| const BasicBlock *PredBB) { |
| PHINode *PN = dyn_cast<PHINode>(this); |
| if (PN && PN->getParent() == CurBB) |
| return PN->getIncomingValueForBlock(PredBB); |
| return this; |
| } |
| |
| LLVMContext &Value::getContext() const { return VTy->getContext(); } |
| |
| //===----------------------------------------------------------------------===// |
| // ValueHandleBase Class |
| //===----------------------------------------------------------------------===// |
| |
| /// AddToExistingUseList - Add this ValueHandle to the use list for VP, where |
| /// List is known to point into the existing use list. |
| void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) { |
| assert(List && "Handle list is null?"); |
| |
| // Splice ourselves into the list. |
| Next = *List; |
| *List = this; |
| setPrevPtr(List); |
| if (Next) { |
| Next->setPrevPtr(&Next); |
| assert(VP.getPointer() == Next->VP.getPointer() && "Added to wrong list?"); |
| } |
| } |
| |
| void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) { |
| assert(List && "Must insert after existing node"); |
| |
| Next = List->Next; |
| setPrevPtr(&List->Next); |
| List->Next = this; |
| if (Next) |
| Next->setPrevPtr(&Next); |
| } |
| |
| /// AddToUseList - Add this ValueHandle to the use list for VP. |
| void ValueHandleBase::AddToUseList() { |
| assert(VP.getPointer() && "Null pointer doesn't have a use list!"); |
| |
| LLVMContextImpl *pImpl = VP.getPointer()->getContext().pImpl; |
| |
| if (VP.getPointer()->HasValueHandle) { |
| // If this value already has a ValueHandle, then it must be in the |
| // ValueHandles map already. |
| ValueHandleBase *&Entry = pImpl->ValueHandles[VP.getPointer()]; |
| assert(Entry != 0 && "Value doesn't have any handles?"); |
| AddToExistingUseList(&Entry); |
| return; |
| } |
| |
| // Ok, it doesn't have any handles yet, so we must insert it into the |
| // DenseMap. However, doing this insertion could cause the DenseMap to |
| // reallocate itself, which would invalidate all of the PrevP pointers that |
| // point into the old table. Handle this by checking for reallocation and |
| // updating the stale pointers only if needed. |
| DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles; |
| const void *OldBucketPtr = Handles.getPointerIntoBucketsArray(); |
| |
| ValueHandleBase *&Entry = Handles[VP.getPointer()]; |
| assert(Entry == 0 && "Value really did already have handles?"); |
| AddToExistingUseList(&Entry); |
| VP.getPointer()->HasValueHandle = true; |
| |
| // If reallocation didn't happen or if this was the first insertion, don't |
| // walk the table. |
| if (Handles.isPointerIntoBucketsArray(OldBucketPtr) || |
| Handles.size() == 1) { |
| return; |
| } |
| |
| // Okay, reallocation did happen. Fix the Prev Pointers. |
| for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(), |
| E = Handles.end(); I != E; ++I) { |
| assert(I->second && I->first == I->second->VP.getPointer() && |
| "List invariant broken!"); |
| I->second->setPrevPtr(&I->second); |
| } |
| } |
| |
| /// RemoveFromUseList - Remove this ValueHandle from its current use list. |
| void ValueHandleBase::RemoveFromUseList() { |
| assert(VP.getPointer() && VP.getPointer()->HasValueHandle && |
| "Pointer doesn't have a use list!"); |
| |
| // Unlink this from its use list. |
| ValueHandleBase **PrevPtr = getPrevPtr(); |
| assert(*PrevPtr == this && "List invariant broken"); |
| |
| *PrevPtr = Next; |
| if (Next) { |
| assert(Next->getPrevPtr() == &Next && "List invariant broken"); |
| Next->setPrevPtr(PrevPtr); |
| return; |
| } |
| |
| // If the Next pointer was null, then it is possible that this was the last |
| // ValueHandle watching VP. If so, delete its entry from the ValueHandles |
| // map. |
| LLVMContextImpl *pImpl = VP.getPointer()->getContext().pImpl; |
| DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles; |
| if (Handles.isPointerIntoBucketsArray(PrevPtr)) { |
| Handles.erase(VP.getPointer()); |
| VP.getPointer()->HasValueHandle = false; |
| } |
| } |
| |
| |
| void ValueHandleBase::ValueIsDeleted(Value *V) { |
| assert(V->HasValueHandle && "Should only be called if ValueHandles present"); |
| |
| // Get the linked list base, which is guaranteed to exist since the |
| // HasValueHandle flag is set. |
| LLVMContextImpl *pImpl = V->getContext().pImpl; |
| ValueHandleBase *Entry = pImpl->ValueHandles[V]; |
| assert(Entry && "Value bit set but no entries exist"); |
| |
| // We use a local ValueHandleBase as an iterator so that ValueHandles can add |
| // and remove themselves from the list without breaking our iteration. This |
| // is not really an AssertingVH; we just have to give ValueHandleBase a kind. |
| // Note that we deliberately do not the support the case when dropping a value |
| // handle results in a new value handle being permanently added to the list |
| // (as might occur in theory for CallbackVH's): the new value handle will not |
| // be processed and the checking code will mete out righteous punishment if |
| // the handle is still present once we have finished processing all the other |
| // value handles (it is fine to momentarily add then remove a value handle). |
| for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) { |
| Iterator.RemoveFromUseList(); |
| Iterator.AddToExistingUseListAfter(Entry); |
| assert(Entry->Next == &Iterator && "Loop invariant broken."); |
| |
| switch (Entry->getKind()) { |
| case Assert: |
| break; |
| case Tracking: |
| // Mark that this value has been deleted by setting it to an invalid Value |
| // pointer. |
| Entry->operator=(DenseMapInfo<Value *>::getTombstoneKey()); |
| break; |
| case Weak: |
| // Weak just goes to null, which will unlink it from the list. |
| Entry->operator=(0); |
| break; |
| case Callback: |
| // Forward to the subclass's implementation. |
| static_cast<CallbackVH*>(Entry)->deleted(); |
| break; |
| } |
| } |
| |
| // All callbacks, weak references, and assertingVHs should be dropped by now. |
| if (V->HasValueHandle) { |
| #ifndef NDEBUG // Only in +Asserts mode... |
| dbgs() << "While deleting: " << *V->getType() << " %" << V->getName() |
| << "\n"; |
| if (pImpl->ValueHandles[V]->getKind() == Assert) |
| llvm_unreachable("An asserting value handle still pointed to this" |
| " value!"); |
| |
| #endif |
| llvm_unreachable("All references to V were not removed?"); |
| } |
| } |
| |
| |
| void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) { |
| assert(Old->HasValueHandle &&"Should only be called if ValueHandles present"); |
| assert(Old != New && "Changing value into itself!"); |
| |
| // Get the linked list base, which is guaranteed to exist since the |
| // HasValueHandle flag is set. |
| LLVMContextImpl *pImpl = Old->getContext().pImpl; |
| ValueHandleBase *Entry = pImpl->ValueHandles[Old]; |
| |
| assert(Entry && "Value bit set but no entries exist"); |
| |
| // We use a local ValueHandleBase as an iterator so that |
| // ValueHandles can add and remove themselves from the list without |
| // breaking our iteration. This is not really an AssertingVH; we |
| // just have to give ValueHandleBase some kind. |
| for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) { |
| Iterator.RemoveFromUseList(); |
| Iterator.AddToExistingUseListAfter(Entry); |
| assert(Entry->Next == &Iterator && "Loop invariant broken."); |
| |
| switch (Entry->getKind()) { |
| case Assert: |
| // Asserting handle does not follow RAUW implicitly. |
| break; |
| case Tracking: |
| // Tracking goes to new value like a WeakVH. Note that this may make it |
| // something incompatible with its templated type. We don't want to have a |
| // virtual (or inline) interface to handle this though, so instead we make |
| // the TrackingVH accessors guarantee that a client never sees this value. |
| |
| // FALLTHROUGH |
| case Weak: |
| // Weak goes to the new value, which will unlink it from Old's list. |
| Entry->operator=(New); |
| break; |
| case Callback: |
| // Forward to the subclass's implementation. |
| static_cast<CallbackVH*>(Entry)->allUsesReplacedWith(New); |
| break; |
| } |
| } |
| |
| #ifndef NDEBUG |
| // If any new tracking or weak value handles were added while processing the |
| // list, then complain about it now. |
| if (Old->HasValueHandle) |
| for (Entry = pImpl->ValueHandles[Old]; Entry; Entry = Entry->Next) |
| switch (Entry->getKind()) { |
| case Tracking: |
| case Weak: |
| dbgs() << "After RAUW from " << *Old->getType() << " %" |
| << Old->getName() << " to " << *New->getType() << " %" |
| << New->getName() << "\n"; |
| llvm_unreachable("A tracking or weak value handle still pointed to the" |
| " old value!\n"); |
| default: |
| break; |
| } |
| #endif |
| } |
| |
| // Default implementation for CallbackVH. |
| void CallbackVH::allUsesReplacedWith(Value *) {} |
| |
| void CallbackVH::deleted() { |
| setValPtr(NULL); |
| } |