RFR: 8303489: Add a test to verify classes in vmStruct have unuque vtables [v2]

[Alex Menkov]

On Thu, 2 Mar 2023 16:06:41 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   addressed feedback
>
> test/hotspot/jtreg/serviceability/sa/UniqueVtableTest.java line 112:
> 
>> 110:             }
>> 111: 
>> 112:             if (vtable == null && t.getSuperclass() != null) {
> 
> Why only log if there is no superclass?

vmStruct contains a lot of entries which should have super == null
I added logging of some stats to the test, on win-x64-fastdebug it reports:
total: 861, no vtable: 503, no_vtable_with_super: 24
if test would log everything with no vtable, test log is truncated

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PR: https://git.openjdk.org/jdk/pull/12820