code: private void generateCacheHitReturn() {
          // stack:
          generateGetFromCache();
          // stack: <cachedValue>
          insert(new InsnNode(DUP));
          // stack: <cachedValue> :: <cachedValue>
          LabelNode cacheMissLabel = new LabelNode();
          insert(new JumpInsnNode(IFNULL, cacheMissLabel));
          // stack: <cachedValue>
          insert(new InsnNode(ARETURN));
          // stack: <null>
          insert(cacheMissLabel);
          // stack: <null>
          insert(new InsnNode(POP));
          // stack:
      }
docs: if (<cache> != null) return <cache>;