Integrated: 8267186: Add string deduplication support to ZGC

[Per Liden]

On Fri, 6 Aug 2021 10:03:05 GMT, Per Liden <pliden at openjdk.org> wrote:

> This change adds support for string deduplication to ZGC. It's a pretty straight forward change, but to make reviewing even easier it is broken up into two commits:
> 
> __ZGC: Introduce ZMarkContext__
> This commit just moves the `ZMarkCache` into the new `ZMarkContext` class, and we now pass a `ZMarkContext*` around instead of a `ZMarkCache*`. The `ZMarkContext` class is a more general container for worker-local data, which in the next commit will be extended to also include the `StringDedup::Requests` queue.
> 
> __8267186: Add string deduplication support to ZGC__
> This commits adds the actual string dedup functionality and enables relevant tests. We use the `deduplication_requested` bit in the `String` object to filter out `Strings` we've already attempted to deduplicate.
> 
> Testing:
> - Passes all string dedup tests.
> - Passes Tier1-7 with ZGC on Linux/x86_64 (with -XX:+UseStringDeduplication enabled by default to get better exposure).

This pull request has now been integrated.

Changeset: abebbe23
Author:    Per Liden <pliden at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/abebbe2335a6dc9b12e5f271bf32cdc54f80b660
Stats:     255 lines in 11 files changed: 219 ins; 9 del; 27 mod

8267186: Add string deduplication support to ZGC

Reviewed-by: eosterlund, kbarrett, stefank

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PR: https://git.openjdk.java.net/jdk/pull/5029