src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.nodes/src/org/graalvm/compiler/nodes/cfg/ControlFlowGraph.java

@@ -590,11 +590,15 @@
         if (graph.hasLoops()) {
             Block[] stack = new Block[this.reversePostOrder.length];
             for (Block block : reversePostOrder) {
                 AbstractBeginNode beginNode = block.getBeginNode();
                 if (beginNode instanceof LoopBeginNode) {
-                    Loop<Block> loop = new HIRLoop(block.getLoop(), loops.size(), block);
+                    Loop<Block> parent = block.getLoop();
+                    Loop<Block> loop = new HIRLoop(parent, loops.size(), block);
+                    if (parent != null) {
+                        parent.getChildren().add(loop);
+                    }
                     loops.add(loop);
                     block.setLoop(loop);
                     loop.getBlocks().add(block);
 
                     LoopBeginNode loopBegin = (LoopBeginNode) beginNode;