The fix for JDK-8242453 relaxed the assert in MemNode::optimize_memory_chain because loads from a non-flat array can be pushed through an arraycopy from a flat array (see LoadNode::can_see_arraycopy_value) and end up with an inconsistent memory input (oop load from flat array). The checks emitted for the arraycopy will catch this and the load will be removed but optimize_memory_chain() can still be executed before that happens.