[lilliput-jdk17u:lilliput] RFR: 8310944: [Lilliput/JDK17] Streamline and cleanup GC code [v3]

[Aleksey Shipilev]

On Thu, 29 Jun 2023 14:25:26 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> We have a bunch of ugly hacks in GC code paths where we do stuff like:
>> if (UseCompactObjectHeaders) {
>>  // fetch object Klass* or size in a safe way...
>> } else {
>>   // fetch object Klass* or size in the traditional way
>> }
>> 
>> This happens in various places in similar ways. I propose to add relevant methods to oopDesc, and make all GC code use those new methods instead.
>> 
>> This helps streamline and clean up a bunch of GC code, and bring it closer to the JDK22 upstreaming PR.
>> 
>> Testing:
>>  - [x] hotspot_gc
>>  - [x] hotspot_gc (+UCOH)
>>  - [x] tier1
>>  - [x] tier1 (+ShenandoahGC)
>>  - [x] tier1 (+ParallelGC)
>>  - [x] tier1 (+SerialGC)
>>  - [x] tier1 (+UCOH)
>>  - [x] tier1 (+UCOH +ShenandoahGC)
>>  - [x] tier1 (+UCOH +ParallelGC)
>>  - [x] tier1 (+UCOH +SerialGC)
>>  - [ ] tier2
>>  - [ ] tier2 (+UCOH)
>
> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix oopDesc::init_mark() and use it where appropriate

OK!

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/lilliput-jdk17u/pull/50#pullrequestreview-1505504533