RFR: 8371783: Refactor GCCause in VM_CollectForMetadataAllocation [v2]

[Albert Mingkun Yang]

On Wed, 19 Nov 2025 16:11:42 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

>> Hello,
>> 
>> We should improve how we use and set GCCause in VM_CollectForMetadataAllocation to make it more clear when reading the code what is going on.
>> 
>> When constructing a VM_CollectForMetadataAllocation operation, we pass in a GCCause, which is not always the cause that is used, since we might also have to clear soft references as a last resort if earlier collection attemps is not enough to free up memory.
>> 
>> The GCCauseSetter at the start of this operation is also redundant as subsequent calls to initiate a GC set the cause themselves.
>> 
>> Testing:
>> * Oracle's tier1-3
>
> Joel Sikström has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Move heap variable down a bit

Marked as reviewed by ayang (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/28287#pullrequestreview-3484805596