RFR: 8353273: Reduce number of oop map entries in instances [v2]

[Thomas Stuefe]

On Thu, 3 Apr 2025 22:45:27 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

>> Thomas Stuefe has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
>> 
>>  - add regression test
>>  - Reworked to use prior super klass layout reconstruction pass
>>  - Merge branch 'master' into JDK-8353273-Reduce-average-number-of-oop-map-entries-in-instance-objects
>>  - alternate-order
>>  - print
>
> test/hotspot/jtreg/runtime/FieldLayout/TestOopMapSizeMinimal.java line 94:
> 
>> 92:     static {
>> 93:         WhiteBox WB = WhiteBox.getWhiteBox();
>> 94:         boolean is_64_bit = System.getProperty("sun.arch.data.model").equals("64");
> 
> I am a little bit confused with this check 
> and
> `*` @requires vm.bits == "64"`
> Shouldn't "sun.arch.data.model" be always 64?

Thank you. Copy-paste error. I fixed the tests.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24330#discussion_r2032424032