+ return V->getValueID() == MetadataAsValueVal;
+ }
+
+private:
+ void handleChangedMetadata(Metadata *MD);
+ void track();
+ void untrack();
+};
+
+/// \brief Shared implementation of use-lists for replaceable metadata.
+///
+/// Most metadata cannot be RAUW'ed. This is a shared implementation of
+/// use-lists and associated API for the two that support it (\a ValueAsMetadata
+/// and \a TempMDNode).
+class ReplaceableMetadataImpl {
+ friend class MetadataTracking;
+
+public:
+ typedef MetadataTracking::OwnerTy OwnerTy;
+
+private:
+ SmallDenseMap<void *, OwnerTy, 4> UseMap;
+
+public:
+ ~ReplaceableMetadataImpl() {
+ assert(UseMap.empty() && "Cannot destroy in-use replaceable metadata");
+ }
+
+ /// \brief Replace all uses of this with MD.
+ ///
+ /// Replace all uses of this with \c MD, which is allowed to be null.
+ void replaceAllUsesWith(Metadata *MD);
+
+ /// \brief Resolve all uses of this.
+ ///
+ /// Resolve all uses of this, turning off RAUW permanently. If \c
+ /// ResolveUsers, call \a GenericMDNode::resolve() on any users whose last
+ /// operand is resolved.
+ void resolveAllUses(bool ResolveUsers = true);
+
+private:
+ void addRef(void *Ref, OwnerTy Owner);
+ void dropRef(void *Ref);
+ void moveRef(void *Ref, void *New, const Metadata &MD);
+
+ static ReplaceableMetadataImpl *get(Metadata &MD);
+};
+
+/// \brief Value wrapper in the Metadata hierarchy.
+///
+/// This is a custom value handle that allows other metadata to refer to
+/// classes in the Value hierarchy.
+///
+/// Because of full uniquing support, each value is only wrapped by a single \a
+/// ValueAsMetadata object, so the lookup maps are far more efficient than
+/// those using ValueHandleBase.
+class ValueAsMetadata : public Metadata, ReplaceableMetadataImpl {
+ friend class ReplaceableMetadataImpl;
+ friend class LLVMContextImpl;
+
+ Value *V;
+
+protected:
+ ValueAsMetadata(LLVMContext &Context, unsigned ID, Value *V)
+ : Metadata(ID), V(V) {
+ assert(V && "Expected valid value");
+ }
+ ~ValueAsMetadata() {}
+
+public:
+ static ValueAsMetadata *get(Value *V);
+ static ConstantAsMetadata *getConstant(Value *C) {
+ return cast<ConstantAsMetadata>(get(C));
+ }
+ static LocalAsMetadata *getLocal(Value *Local) {
+ return cast<LocalAsMetadata>(get(Local));
+ }
+
+ static ValueAsMetadata *getIfExists(Value *V);
+ static ConstantAsMetadata *getConstantIfExists(Value *C) {
+ return cast_or_null<ConstantAsMetadata>(getIfExists(C));
+ }
+ static LocalAsMetadata *getLocalIfExists(Value *Local) {
+ return cast_or_null<LocalAsMetadata>(getIfExists(Local));
+ }
+
+ Value *getValue() const { return V; }
+ Type *getType() const { return V->getType(); }
+ LLVMContext &getContext() const { return V->getContext(); }
+
+ static void handleDeletion(Value *V);
+ static void handleRAUW(Value *From, Value *To);
+
+protected:
+ /// \brief Handle collisions after \a Value::replaceAllUsesWith().
+ ///
+ /// RAUW isn't supported directly for \a ValueAsMetadata, but if the wrapped
+ /// \a Value gets RAUW'ed and the target already exists, this is used to
+ /// merge the two metadata nodes.
+ void replaceAllUsesWith(Metadata *MD) {
+ ReplaceableMetadataImpl::replaceAllUsesWith(MD);
+ }
+
+public:
+ static bool classof(const Metadata *MD) {
+ return MD->getMetadataID() == LocalAsMetadataKind ||
+ MD->getMetadataID() == ConstantAsMetadataKind;
+ }
+};
+
+class ConstantAsMetadata : public ValueAsMetadata {
+ friend class ValueAsMetadata;
+
+ ConstantAsMetadata(LLVMContext &Context, Constant *C)
+ : ValueAsMetadata(Context, ConstantAsMetadataKind, C) {}
+
+public:
+ static ConstantAsMetadata *get(Constant *C) {
+ return ValueAsMetadata::getConstant(C);
+ }
+ static ConstantAsMetadata *getIfExists(Constant *C) {
+ return ValueAsMetadata::getConstantIfExists(C);
+ }
+
+ Constant *getValue() const {
+ return cast<Constant>(ValueAsMetadata::getValue());
+ }
+
+ static bool classof(const Metadata *MD) {
+ return MD->getMetadataID() == ConstantAsMetadataKind;
+ }
+};
+
+class LocalAsMetadata : public ValueAsMetadata {
+ friend class ValueAsMetadata;
+
+ LocalAsMetadata(LLVMContext &Context, Value *Local)
+ : ValueAsMetadata(Context, LocalAsMetadataKind, Local) {
+ assert(!isa<Constant>(Local) && "Expected local value");
+ }
+
+public:
+ static LocalAsMetadata *get(Value *Local) {
+ return ValueAsMetadata::getLocal(Local);