[master] RFR: Preserve Klass* in leak profiler

[Aleksey Shipilev]

On Wed, 13 Oct 2021 09:32:58 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> The JFR leak profiler uses the mark word for marking objects during traversal, and for storing pointers to Edges. We need to preserve the compressed Klass* in the upper part of the mark-word during the traversal.
> 
> The change is based on: ttps://github.com/openjdk/jdk/pull/5918
> 
> Testing:
>  - [x] jdk/jfr (x86_64)
>  - [x] jdk/jfr (x86_32)
>  - [x] tier1
>  - [ ] tier2

All right. This is cherry-pick of upstream change, right? Looks good then.

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Marked as reviewed by shade (Committer).

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