+/// Resolve uniquing cycles involving the given metadata.
+static void resolveCycles(Metadata *MD) {
+ if (auto *N = dyn_cast_or_null<MDNode>(MD))
+ if (!N->isResolved())
+ N->resolveCycles();
+}
+
+/// Remap the operands of an MDNode.
+///
+/// If \c Node is temporary, uniquing cycles are ignored. If \c Node is
+/// distinct, uniquing cycles are resolved as they're found.
+///
+/// \pre \c Node.isDistinct() or \c Node.isTemporary().
+static bool remapOperands(MDNode &Node,
+ SmallVectorImpl<MDNode *> &DistinctWorklist,
+ ValueToValueMapTy &VM, RemapFlags Flags,
+ ValueMapTypeRemapper *TypeMapper,
+ ValueMaterializer *Materializer) {
+ assert(!Node.isUniqued() && "Expected temporary or distinct node");
+ const bool IsDistinct = Node.isDistinct();
+
+ bool AnyChanged = false;
+ for (unsigned I = 0, E = Node.getNumOperands(); I != E; ++I) {
+ Metadata *Old = Node.getOperand(I);
+ Metadata *New = mapMetadataOp(Old, DistinctWorklist, VM, Flags, TypeMapper,
+ Materializer);
+ if (Old != New) {
+ AnyChanged = true;
+ Node.replaceOperandWith(I, New);
+
+ // Resolve uniquing cycles underneath distinct nodes on the fly so they
+ // don't infect later operands.
+ if (IsDistinct)
+ resolveCycles(New);
+ }
+ }
+
+ return AnyChanged;
+}
+
+/// Map a distinct MDNode.