1 //===-- Value.cpp - Implement the Value class -----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the Value, ValueHandle, and User classes.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/IR/Value.h"
15 #include "LLVMContextImpl.h"
16 #include "llvm/ADT/DenseMap.h"
17 #include "llvm/ADT/SmallString.h"
18 #include "llvm/IR/CallSite.h"
19 #include "llvm/IR/Constant.h"
20 #include "llvm/IR/Constants.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/DerivedTypes.h"
23 #include "llvm/IR/GetElementPtrTypeIterator.h"
24 #include "llvm/IR/InstrTypes.h"
25 #include "llvm/IR/Instructions.h"
26 #include "llvm/IR/IntrinsicInst.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/IR/Operator.h"
29 #include "llvm/IR/Statepoint.h"
30 #include "llvm/IR/ValueHandle.h"
31 #include "llvm/IR/ValueSymbolTable.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/ManagedStatic.h"
38 //===----------------------------------------------------------------------===//
40 //===----------------------------------------------------------------------===//
42 static inline Type *checkType(Type *Ty) {
43 assert(Ty && "Value defined with a null type: Error!");
47 Value::Value(Type *ty, unsigned scid)
48 : VTy(checkType(ty)), UseList(nullptr), SubclassID(scid), HasValueHandle(0),
49 SubclassOptionalData(0), SubclassData(0), NumOperands(0) {
50 // FIXME: Why isn't this in the subclass gunk??
51 // Note, we cannot call isa<CallInst> before the CallInst has been
53 if (SubclassID == Instruction::Call || SubclassID == Instruction::Invoke)
54 assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) &&
55 "invalid CallInst type!");
56 else if (SubclassID != BasicBlockVal &&
57 (SubclassID < ConstantFirstVal || SubclassID > ConstantLastVal))
58 assert((VTy->isFirstClassType() || VTy->isVoidTy()) &&
59 "Cannot create non-first-class values except for constants!");
63 // Notify all ValueHandles (if present) that this value is going away.
65 ValueHandleBase::ValueIsDeleted(this);
66 if (isUsedByMetadata())
67 ValueAsMetadata::handleDeletion(this);
69 #ifndef NDEBUG // Only in -g mode...
70 // Check to make sure that there are no uses of this value that are still
71 // around when the value is destroyed. If there are, then we have a dangling
72 // reference and something is wrong. This code is here to print out where
73 // the value is still being referenced.
76 dbgs() << "While deleting: " << *VTy << " %" << getName() << "\n";
77 for (auto *U : users())
78 dbgs() << "Use still stuck around after Def is destroyed:" << *U << "\n";
81 assert(use_empty() && "Uses remain when a value is destroyed!");
83 // If this value is named, destroy the name. This should not be in a symtab
88 void Value::destroyValueName() {
89 ValueName *Name = getValueName();
92 setValueName(nullptr);
95 bool Value::hasNUses(unsigned N) const {
96 const_use_iterator UI = use_begin(), E = use_end();
99 if (UI == E) return false; // Too few.
103 bool Value::hasNUsesOrMore(unsigned N) const {
104 const_use_iterator UI = use_begin(), E = use_end();
107 if (UI == E) return false; // Too few.
112 bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
113 // This can be computed either by scanning the instructions in BB, or by
114 // scanning the use list of this Value. Both lists can be very long, but
115 // usually one is quite short.
117 // Scan both lists simultaneously until one is exhausted. This limits the
118 // search to the shorter list.
119 BasicBlock::const_iterator BI = BB->begin(), BE = BB->end();
120 const_user_iterator UI = user_begin(), UE = user_end();
121 for (; BI != BE && UI != UE; ++BI, ++UI) {
122 // Scan basic block: Check if this Value is used by the instruction at BI.
123 if (std::find(BI->op_begin(), BI->op_end(), this) != BI->op_end())
125 // Scan use list: Check if the use at UI is in BB.
126 const Instruction *User = dyn_cast<Instruction>(*UI);
127 if (User && User->getParent() == BB)
133 unsigned Value::getNumUses() const {
134 return (unsigned)std::distance(use_begin(), use_end());
137 static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
139 if (Instruction *I = dyn_cast<Instruction>(V)) {
140 if (BasicBlock *P = I->getParent())
141 if (Function *PP = P->getParent())
142 ST = &PP->getValueSymbolTable();
143 } else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
144 if (Function *P = BB->getParent())
145 ST = &P->getValueSymbolTable();
146 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
147 if (Module *P = GV->getParent())
148 ST = &P->getValueSymbolTable();
149 } else if (Argument *A = dyn_cast<Argument>(V)) {
150 if (Function *P = A->getParent())
151 ST = &P->getValueSymbolTable();
153 assert(isa<Constant>(V) && "Unknown value type!");
154 return true; // no name is setable for this.
159 StringRef Value::getName() const {
160 // Make sure the empty string is still a C string. For historical reasons,
161 // some clients want to call .data() on the result and expect it to be null
164 return StringRef("", 0);
165 return getValueName()->getKey();
168 void Value::setName(const Twine &NewName) {
169 // Fast path for common IRBuilder case of setName("") when there is no name.
170 if (NewName.isTriviallyEmpty() && !hasName())
173 SmallString<256> NameData;
174 StringRef NameRef = NewName.toStringRef(NameData);
175 assert(NameRef.find_first_of(0) == StringRef::npos &&
176 "Null bytes are not allowed in names");
178 // Name isn't changing?
179 if (getName() == NameRef)
182 assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");
184 // Get the symbol table to update for this object.
185 ValueSymbolTable *ST;
186 if (getSymTab(this, ST))
187 return; // Cannot set a name on this value (e.g. constant).
189 if (Function *F = dyn_cast<Function>(this))
190 getContext().pImpl->IntrinsicIDCache.erase(F);
192 if (!ST) { // No symbol table to update? Just do the change.
193 if (NameRef.empty()) {
194 // Free the name for this value.
199 // NOTE: Could optimize for the case the name is shrinking to not deallocate
203 // Create the new name.
204 setValueName(ValueName::Create(NameRef));
205 getValueName()->setValue(this);
209 // NOTE: Could optimize for the case the name is shrinking to not deallocate
213 ST->removeValueName(getValueName());
220 // Name is changing to something new.
221 setValueName(ST->createValueName(NameRef, this));
224 void Value::takeName(Value *V) {
225 ValueSymbolTable *ST = nullptr;
226 // If this value has a name, drop it.
228 // Get the symtab this is in.
229 if (getSymTab(this, ST)) {
230 // We can't set a name on this value, but we need to clear V's name if
232 if (V->hasName()) V->setName("");
233 return; // Cannot set a name on this value (e.g. constant).
238 ST->removeValueName(getValueName());
242 // Now we know that this has no name.
244 // If V has no name either, we're done.
245 if (!V->hasName()) return;
247 // Get this's symtab if we didn't before.
249 if (getSymTab(this, ST)) {
252 return; // Cannot set a name on this value (e.g. constant).
256 // Get V's ST, this should always succed, because V has a name.
257 ValueSymbolTable *VST;
258 bool Failure = getSymTab(V, VST);
259 assert(!Failure && "V has a name, so it should have a ST!"); (void)Failure;
261 // If these values are both in the same symtab, we can do this very fast.
262 // This works even if both values have no symtab yet.
265 setValueName(V->getValueName());
266 V->setValueName(nullptr);
267 getValueName()->setValue(this);
271 // Otherwise, things are slightly more complex. Remove V's name from VST and
272 // then reinsert it into ST.
275 VST->removeValueName(V->getValueName());
276 setValueName(V->getValueName());
277 V->setValueName(nullptr);
278 getValueName()->setValue(this);
281 ST->reinsertValue(this);
285 static bool contains(SmallPtrSetImpl<ConstantExpr *> &Cache, ConstantExpr *Expr,
287 if (!Cache.insert(Expr).second)
290 for (auto &O : Expr->operands()) {
293 auto *CE = dyn_cast<ConstantExpr>(O);
296 if (contains(Cache, CE, C))
302 static bool contains(Value *Expr, Value *V) {
306 auto *C = dyn_cast<Constant>(V);
310 auto *CE = dyn_cast<ConstantExpr>(Expr);
314 SmallPtrSet<ConstantExpr *, 4> Cache;
315 return contains(Cache, CE, C);
319 void Value::replaceAllUsesWith(Value *New) {
320 assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
321 assert(!contains(New, this) &&
322 "this->replaceAllUsesWith(expr(this)) is NOT valid!");
323 assert(New->getType() == getType() &&
324 "replaceAllUses of value with new value of different type!");
326 // Notify all ValueHandles (if present) that this value is going away.
328 ValueHandleBase::ValueIsRAUWd(this, New);
329 if (isUsedByMetadata())
330 ValueAsMetadata::handleRAUW(this, New);
332 while (!use_empty()) {
334 // Must handle Constants specially, we cannot call replaceUsesOfWith on a
335 // constant because they are uniqued.
336 if (auto *C = dyn_cast<Constant>(U.getUser())) {
337 if (!isa<GlobalValue>(C)) {
338 C->replaceUsesOfWithOnConstant(this, New, &U);
346 if (BasicBlock *BB = dyn_cast<BasicBlock>(this))
347 BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New));
350 // Like replaceAllUsesWith except it does not handle constants or basic blocks.
351 // This routine leaves uses within BB.
352 void Value::replaceUsesOutsideBlock(Value *New, BasicBlock *BB) {
353 assert(New && "Value::replaceUsesOutsideBlock(<null>, BB) is invalid!");
354 assert(!contains(New, this) &&
355 "this->replaceUsesOutsideBlock(expr(this), BB) is NOT valid!");
356 assert(New->getType() == getType() &&
357 "replaceUses of value with new value of different type!");
358 assert(BB && "Basic block that may contain a use of 'New' must be defined\n");
360 use_iterator UI = use_begin(), E = use_end();
364 auto *Usr = dyn_cast<Instruction>(U.getUser());
365 if (Usr && Usr->getParent() == BB)
373 // Various metrics for how much to strip off of pointers.
374 enum PointerStripKind {
376 PSK_ZeroIndicesAndAliases,
377 PSK_InBoundsConstantIndices,
381 template <PointerStripKind StripKind>
382 static Value *stripPointerCastsAndOffsets(Value *V) {
383 if (!V->getType()->isPointerTy())
386 // Even though we don't look through PHI nodes, we could be called on an
387 // instruction in an unreachable block, which may be on a cycle.
388 SmallPtrSet<Value *, 4> Visited;
392 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
394 case PSK_ZeroIndicesAndAliases:
395 case PSK_ZeroIndices:
396 if (!GEP->hasAllZeroIndices())
399 case PSK_InBoundsConstantIndices:
400 if (!GEP->hasAllConstantIndices())
404 if (!GEP->isInBounds())
408 V = GEP->getPointerOperand();
409 } else if (Operator::getOpcode(V) == Instruction::BitCast ||
410 Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
411 V = cast<Operator>(V)->getOperand(0);
412 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
413 if (StripKind == PSK_ZeroIndices || GA->mayBeOverridden())
415 V = GA->getAliasee();
419 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
420 } while (Visited.insert(V).second);
426 Value *Value::stripPointerCasts() {
427 return stripPointerCastsAndOffsets<PSK_ZeroIndicesAndAliases>(this);
430 Value *Value::stripPointerCastsNoFollowAliases() {
431 return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this);
434 Value *Value::stripInBoundsConstantOffsets() {
435 return stripPointerCastsAndOffsets<PSK_InBoundsConstantIndices>(this);
438 Value *Value::stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
440 if (!getType()->isPointerTy())
443 assert(Offset.getBitWidth() == DL.getPointerSizeInBits(cast<PointerType>(
444 getType())->getAddressSpace()) &&
445 "The offset must have exactly as many bits as our pointer.");
447 // Even though we don't look through PHI nodes, we could be called on an
448 // instruction in an unreachable block, which may be on a cycle.
449 SmallPtrSet<Value *, 4> Visited;
450 Visited.insert(this);
453 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
454 if (!GEP->isInBounds())
456 APInt GEPOffset(Offset);
457 if (!GEP->accumulateConstantOffset(DL, GEPOffset))
460 V = GEP->getPointerOperand();
461 } else if (Operator::getOpcode(V) == Instruction::BitCast ||
462 Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
463 V = cast<Operator>(V)->getOperand(0);
464 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
465 V = GA->getAliasee();
469 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
470 } while (Visited.insert(V).second);
475 Value *Value::stripInBoundsOffsets() {
476 return stripPointerCastsAndOffsets<PSK_InBounds>(this);
479 /// \brief Check if Value is always a dereferenceable pointer.
481 /// Test if V is always a pointer to allocated and suitably aligned memory for
482 /// a simple load or store.
483 static bool isDereferenceablePointer(const Value *V, const DataLayout &DL,
484 SmallPtrSetImpl<const Value *> &Visited) {
485 // Note that it is not safe to speculate into a malloc'd region because
486 // malloc may return null.
488 // These are obviously ok.
489 if (isa<AllocaInst>(V)) return true;
491 // It's not always safe to follow a bitcast, for example:
492 // bitcast i8* (alloca i8) to i32*
493 // would result in a 4-byte load from a 1-byte alloca. However,
494 // if we're casting from a pointer from a type of larger size
495 // to a type of smaller size (or the same size), and the alignment
496 // is at least as large as for the resulting pointer type, then
497 // we can look through the bitcast.
498 if (const BitCastOperator *BC = dyn_cast<BitCastOperator>(V)) {
499 Type *STy = BC->getSrcTy()->getPointerElementType(),
500 *DTy = BC->getDestTy()->getPointerElementType();
501 if (STy->isSized() && DTy->isSized() &&
502 (DL.getTypeStoreSize(STy) >= DL.getTypeStoreSize(DTy)) &&
503 (DL.getABITypeAlignment(STy) >= DL.getABITypeAlignment(DTy)))
504 return isDereferenceablePointer(BC->getOperand(0), DL, Visited);
507 // Global variables which can't collapse to null are ok.
508 if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
509 return !GV->hasExternalWeakLinkage();
511 // byval arguments are okay. Arguments specifically marked as
512 // dereferenceable are okay too.
513 if (const Argument *A = dyn_cast<Argument>(V)) {
514 if (A->hasByValAttr())
516 else if (uint64_t Bytes = A->getDereferenceableBytes()) {
517 Type *Ty = V->getType()->getPointerElementType();
518 if (Ty->isSized() && DL.getTypeStoreSize(Ty) <= Bytes)
525 // Return values from call sites specifically marked as dereferenceable are
527 if (ImmutableCallSite CS = V) {
528 if (uint64_t Bytes = CS.getDereferenceableBytes(0)) {
529 Type *Ty = V->getType()->getPointerElementType();
530 if (Ty->isSized() && DL.getTypeStoreSize(Ty) <= Bytes)
535 // For GEPs, determine if the indexing lands within the allocated object.
536 if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
537 // Conservatively require that the base pointer be fully dereferenceable.
538 if (!Visited.insert(GEP->getOperand(0)).second)
540 if (!isDereferenceablePointer(GEP->getOperand(0), DL, Visited))
542 // Check the indices.
543 gep_type_iterator GTI = gep_type_begin(GEP);
544 for (User::const_op_iterator I = GEP->op_begin()+1,
545 E = GEP->op_end(); I != E; ++I) {
548 // Struct indices can't be out of bounds.
549 if (isa<StructType>(Ty))
551 ConstantInt *CI = dyn_cast<ConstantInt>(Index);
554 // Zero is always ok.
557 // Check to see that it's within the bounds of an array.
558 ArrayType *ATy = dyn_cast<ArrayType>(Ty);
561 if (CI->getValue().getActiveBits() > 64)
563 if (CI->getZExtValue() >= ATy->getNumElements())
566 // Indices check out; this is dereferenceable.
570 // For gc.relocate, look through relocations
571 if (const IntrinsicInst *I = dyn_cast<IntrinsicInst>(V))
572 if (I->getIntrinsicID() == Intrinsic::experimental_gc_relocate) {
573 GCRelocateOperands RelocateInst(I);
574 return isDereferenceablePointer(RelocateInst.derivedPtr(), DL, Visited);
577 if (const AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(V))
578 return isDereferenceablePointer(ASC->getOperand(0), DL, Visited);
580 // If we don't know, assume the worst.
584 bool Value::isDereferenceablePointer(const DataLayout &DL) const {
585 // When dereferenceability information is provided by a dereferenceable
586 // attribute, we know exactly how many bytes are dereferenceable. If we can
587 // determine the exact offset to the attributed variable, we can use that
589 Type *Ty = getType()->getPointerElementType();
591 APInt Offset(DL.getTypeStoreSizeInBits(getType()), 0);
592 const Value *BV = stripAndAccumulateInBoundsConstantOffsets(DL, Offset);
594 APInt DerefBytes(Offset.getBitWidth(), 0);
595 if (const Argument *A = dyn_cast<Argument>(BV))
596 DerefBytes = A->getDereferenceableBytes();
597 else if (ImmutableCallSite CS = BV)
598 DerefBytes = CS.getDereferenceableBytes(0);
600 if (DerefBytes.getBoolValue() && Offset.isNonNegative()) {
601 if (DerefBytes.uge(Offset + DL.getTypeStoreSize(Ty)))
606 SmallPtrSet<const Value *, 32> Visited;
607 return ::isDereferenceablePointer(this, DL, Visited);
610 Value *Value::DoPHITranslation(const BasicBlock *CurBB,
611 const BasicBlock *PredBB) {
612 PHINode *PN = dyn_cast<PHINode>(this);
613 if (PN && PN->getParent() == CurBB)
614 return PN->getIncomingValueForBlock(PredBB);
618 LLVMContext &Value::getContext() const { return VTy->getContext(); }
620 void Value::reverseUseList() {
621 if (!UseList || !UseList->Next)
622 // No need to reverse 0 or 1 uses.
626 Use *Current = UseList->Next;
627 Head->Next = nullptr;
629 Use *Next = Current->Next;
630 Current->Next = Head;
631 Head->setPrev(&Current->Next);
636 Head->setPrev(&UseList);
639 //===----------------------------------------------------------------------===//
640 // ValueHandleBase Class
641 //===----------------------------------------------------------------------===//
643 void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
644 assert(List && "Handle list is null?");
646 // Splice ourselves into the list.
651 Next->setPrevPtr(&Next);
652 assert(V == Next->V && "Added to wrong list?");
656 void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) {
657 assert(List && "Must insert after existing node");
660 setPrevPtr(&List->Next);
663 Next->setPrevPtr(&Next);
666 void ValueHandleBase::AddToUseList() {
667 assert(V && "Null pointer doesn't have a use list!");
669 LLVMContextImpl *pImpl = V->getContext().pImpl;
671 if (V->HasValueHandle) {
672 // If this value already has a ValueHandle, then it must be in the
673 // ValueHandles map already.
674 ValueHandleBase *&Entry = pImpl->ValueHandles[V];
675 assert(Entry && "Value doesn't have any handles?");
676 AddToExistingUseList(&Entry);
680 // Ok, it doesn't have any handles yet, so we must insert it into the
681 // DenseMap. However, doing this insertion could cause the DenseMap to
682 // reallocate itself, which would invalidate all of the PrevP pointers that
683 // point into the old table. Handle this by checking for reallocation and
684 // updating the stale pointers only if needed.
685 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
686 const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
688 ValueHandleBase *&Entry = Handles[V];
689 assert(!Entry && "Value really did already have handles?");
690 AddToExistingUseList(&Entry);
691 V->HasValueHandle = true;
693 // If reallocation didn't happen or if this was the first insertion, don't
695 if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
696 Handles.size() == 1) {
700 // Okay, reallocation did happen. Fix the Prev Pointers.
701 for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
702 E = Handles.end(); I != E; ++I) {
703 assert(I->second && I->first == I->second->V &&
704 "List invariant broken!");
705 I->second->setPrevPtr(&I->second);
709 void ValueHandleBase::RemoveFromUseList() {
710 assert(V && V->HasValueHandle &&
711 "Pointer doesn't have a use list!");
713 // Unlink this from its use list.
714 ValueHandleBase **PrevPtr = getPrevPtr();
715 assert(*PrevPtr == this && "List invariant broken");
719 assert(Next->getPrevPtr() == &Next && "List invariant broken");
720 Next->setPrevPtr(PrevPtr);
724 // If the Next pointer was null, then it is possible that this was the last
725 // ValueHandle watching VP. If so, delete its entry from the ValueHandles
727 LLVMContextImpl *pImpl = V->getContext().pImpl;
728 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
729 if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
731 V->HasValueHandle = false;
736 void ValueHandleBase::ValueIsDeleted(Value *V) {
737 assert(V->HasValueHandle && "Should only be called if ValueHandles present");
739 // Get the linked list base, which is guaranteed to exist since the
740 // HasValueHandle flag is set.
741 LLVMContextImpl *pImpl = V->getContext().pImpl;
742 ValueHandleBase *Entry = pImpl->ValueHandles[V];
743 assert(Entry && "Value bit set but no entries exist");
745 // We use a local ValueHandleBase as an iterator so that ValueHandles can add
746 // and remove themselves from the list without breaking our iteration. This
747 // is not really an AssertingVH; we just have to give ValueHandleBase a kind.
748 // Note that we deliberately do not the support the case when dropping a value
749 // handle results in a new value handle being permanently added to the list
750 // (as might occur in theory for CallbackVH's): the new value handle will not
751 // be processed and the checking code will mete out righteous punishment if
752 // the handle is still present once we have finished processing all the other
753 // value handles (it is fine to momentarily add then remove a value handle).
754 for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
755 Iterator.RemoveFromUseList();
756 Iterator.AddToExistingUseListAfter(Entry);
757 assert(Entry->Next == &Iterator && "Loop invariant broken.");
759 switch (Entry->getKind()) {
763 // Mark that this value has been deleted by setting it to an invalid Value
765 Entry->operator=(DenseMapInfo<Value *>::getTombstoneKey());
768 // Weak just goes to null, which will unlink it from the list.
769 Entry->operator=(nullptr);
772 // Forward to the subclass's implementation.
773 static_cast<CallbackVH*>(Entry)->deleted();
778 // All callbacks, weak references, and assertingVHs should be dropped by now.
779 if (V->HasValueHandle) {
780 #ifndef NDEBUG // Only in +Asserts mode...
781 dbgs() << "While deleting: " << *V->getType() << " %" << V->getName()
783 if (pImpl->ValueHandles[V]->getKind() == Assert)
784 llvm_unreachable("An asserting value handle still pointed to this"
788 llvm_unreachable("All references to V were not removed?");
793 void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
794 assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
795 assert(Old != New && "Changing value into itself!");
796 assert(Old->getType() == New->getType() &&
797 "replaceAllUses of value with new value of different type!");
799 // Get the linked list base, which is guaranteed to exist since the
800 // HasValueHandle flag is set.
801 LLVMContextImpl *pImpl = Old->getContext().pImpl;
802 ValueHandleBase *Entry = pImpl->ValueHandles[Old];
804 assert(Entry && "Value bit set but no entries exist");
806 // We use a local ValueHandleBase as an iterator so that
807 // ValueHandles can add and remove themselves from the list without
808 // breaking our iteration. This is not really an AssertingVH; we
809 // just have to give ValueHandleBase some kind.
810 for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
811 Iterator.RemoveFromUseList();
812 Iterator.AddToExistingUseListAfter(Entry);
813 assert(Entry->Next == &Iterator && "Loop invariant broken.");
815 switch (Entry->getKind()) {
817 // Asserting handle does not follow RAUW implicitly.
820 // Tracking goes to new value like a WeakVH. Note that this may make it
821 // something incompatible with its templated type. We don't want to have a
822 // virtual (or inline) interface to handle this though, so instead we make
823 // the TrackingVH accessors guarantee that a client never sees this value.
827 // Weak goes to the new value, which will unlink it from Old's list.
828 Entry->operator=(New);
831 // Forward to the subclass's implementation.
832 static_cast<CallbackVH*>(Entry)->allUsesReplacedWith(New);
838 // If any new tracking or weak value handles were added while processing the
839 // list, then complain about it now.
840 if (Old->HasValueHandle)
841 for (Entry = pImpl->ValueHandles[Old]; Entry; Entry = Entry->Next)
842 switch (Entry->getKind()) {
845 dbgs() << "After RAUW from " << *Old->getType() << " %"
846 << Old->getName() << " to " << *New->getType() << " %"
847 << New->getName() << "\n";
848 llvm_unreachable("A tracking or weak value handle still pointed to the"
856 // Pin the vtable to this file.
857 void CallbackVH::anchor() {}