+/// 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;