Heap verification fails after recent merge

[Aleksey Shipilev]

Hi,

My basic workloads fail heap verification at the end of the run:

#  Internal Error
(/home/shade/trunks/shenandoah-jdk9/hotspot/src/share/vm/gc/shenandoah/shenandoahHeap.cpp:1520),
pid=25322, tid=25343
#  guarantee(obj->is_oop()) failed: is_oop

This probably happens after the recent merge, as my previous builds are
not affected. Even the very basic workload fails:

$ linux-x86_64-normal-server-fastdebug/images/jdk/bin/java
-XX:+UseShenandoahGC Alloc
<crash>

$ cat Alloc.java

public class Alloc {
	public static void main(String... args) throws Exception {
		new Object();
	}
}

Thanks,
-Aleksey