[master] RFR: Preserve Klass* in leak profiler [v3]

[Roman Kennke]

On Mon, 18 Oct 2021 14:13:15 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

> JFR changes looks good. The only thing I am unsure of is the #ifdef _LP64 "has_displaced_mark_helper()", but I assume this is needed for Lilliput.

Yes, it fetches the actual mark-word, even if it has been displaced, and extracts the narrowKlass out of it (upper 32 bits) and puts it back into the marked header. Otherwise we'd loose the Klass information of the object during leakprofiler traversal of the object graph.

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PR: https://git.openjdk.java.net/lilliput/pull/21