RFR: 8341027: Crash in java/runtime/Unsafe/InternalErrorTest when runnig with -XX:-UseCompressedClassPointers

[Stefan Karlsson]

The JVM crashes in the GC because the destroys the length fields of the array it uses as the destination.

One example of the failures you see with this:
# guarantee(p == top()) failed: end of last object must match end of space
...
V [libjvm.so+0x147e054] ContiguousSpace::verify() const+0x1e0 (space.cpp:95)
V [libjvm.so+0x974118] DefNewGeneration::verify()+0x18 (defNewGeneration.cpp:834)
V [libjvm.so+0x1448a88] SerialHeap::verify(VerifyOption)+0x78 (serialHeap.cpp:881)
V [libjvm.so+0x15d9cd0] Universe::verify(VerifyOption, char const*)+0x490 (universe.cpp:1240)
V [libjvm.so+0x1673890] VM_Exit::doit()+0xa0 (universe.hpp:349) 

Fix this by changing the hard-coded 16 to the proper array base offset, which changes depending on the value of UseCompressedClassPointers.

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Commit messages:
 - 8341027: Crash in java/runtime/Unsafe/InternalErrorTest when runnig with -XX:-UseCompressedClassPointers

Changes: https://git.openjdk.org/jdk/pull/21208/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21208&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341027
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21208.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21208/head:pull/21208

PR: https://git.openjdk.org/jdk/pull/21208