[master] Integrated: 8307991: [Lilliput] Use narrow i-hash only when +UseCompactObjectHeaders

[Roman Kennke]

On Fri, 12 May 2023 10:33:45 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> Currently, we use a narrow 25bit identity-hash-code in Lilliput. That is even the case when running without compact object headers, even though we could just as well use the original 31bit identity hash-code then.
> 
> The fix is relatively simple. Also, this brings the code in line with what we're currently proposing in upstream https://github.com/openjdk/jdk/pull/13844.
> 
> Going forward we would trade Klass* bits to get the full 31 i-hash back, and we're going to do that soon, but let's first fix this issue at hand (also in preparation for a clean backport, where we don't currently have the metaspace improvements).
> 
> Testing:
>  - [x] tier1 +UseCompactObjectHeaders
>  - [x] tier2 +UseCompactObjectHeaders
>  - [x] tier1 -UseCompactObjectHeaders
>  - [x] tier2 -UseCompactObjectHeaders

This pull request has now been integrated.

Changeset: 646f6f5e
Author:    Roman Kennke <rkennke at openjdk.org>
URL:       https://git.openjdk.org/lilliput/commit/646f6f5e2ba276bb510ea6460232026d46cede53
Stats:     58 lines in 7 files changed: 42 ins; 0 del; 16 mod

8307991: [Lilliput] Use narrow i-hash only when +UseCompactObjectHeaders

Reviewed-by: shade

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PR: https://git.openjdk.org/lilliput/pull/93