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

[Chris Plummer]

On Thu, 2 Mar 2023 20:42:16 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

>> 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 vtable == 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

In that case is it worth listing the "no vtable" classes that have a superclass? Are they somehow more interesting than those without a superclass?

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