HotSpot C1 doesn't compile this "monitorenter with Phi input", fails with "invalid parsing"

Demo.j

.class public Demo
.super java/lang/Object

.field public static dummy I

.method public static foo(Ljava/lang/Object;Ljava/lang/Object;Z)V
  .limit stack 2
  .limit locals 3

  iload_2
  ifeq Label_lock_other
  aload_0
  goto Label_do_lock
Label_lock_other:
  aload_1
Label_do_lock:
  monitorenter

  getstatic      Demo/dummy I
  iconst_1
  iadd
  putstatic      Demo/dummy I

  iload_2
  ifeq Label_unlock_other
  aload_0
  goto Label_do_unlock
Label_unlock_other:
  aload_1
Label_do_unlock:
  monitorexit
  return
.end method

To compile, download Jasmin and run java -jar jasmin.jar Demo.j.