8244667: Shenandoah: SBC2Support::test_gc_state takes loop for wrong …

…control

Reviewed-by: rkennke

src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp

@@ -879,7 +879,7 @@ void ShenandoahBarrierC2Support::test_gc_state(Node*& ctrl, Node* raw_mem, Node*
   ctrl                  = new IfTrueNode(gc_state_iff);
   test_fail_ctrl        = new IfFalseNode(gc_state_iff);
 
-  IdealLoopTree* loop = phase->get_loop(ctrl);
+  IdealLoopTree* loop = phase->get_loop(old_ctrl);
   phase->register_control(gc_state_iff,   loop, old_ctrl);
   phase->register_control(ctrl,           loop, gc_state_iff);
   phase->register_control(test_fail_ctrl, loop, gc_state_iff);