RFR: 8325467: Support methods with many arguments in C2 [v27]

[Daniel Lundén]

On Tue, 16 Sep 2025 11:03:28 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Daniel Lundén has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 39 commits:
>> 
>>  - Clarify comments in regmask.hpp
>>  - Merge remote-tracking branch 'upstream/master' into many-arguments-8325467+pr-updates
>>  - Address review comments (renaming on the way in a separate PR)
>>  - Update src/hotspot/share/opto/regmask.hpp
>>    
>>    Co-authored-by: Emanuel Peter <emanuel.peter at oracle.com>
>>  - Restore modified java/lang/invoke tests
>>  - Sort includes (new requirement)
>>  - Merge remote-tracking branch 'upstream/master' into many-arguments-8325467+pr-updates
>>  - Add clarifying comments at definitions of register mask sizes
>>  - Fix implicit zero and nullptr checks
>>  - Add deep copy comment
>>  - ... and 29 more: https://git.openjdk.org/jdk/compare/60930a3e...c1f41288
>
> src/hotspot/share/opto/regmask.hpp line 458:
> 
>> 456:   }
>> 457: 
>> 458:   RegMask(const RegMask& rm) : RegMask(rm, nullptr) {}
> 
> Do you want to add `explicit` here?
> This is a shallow copy, right? Maybe add a comment for that.

The ADLC-generated code relies on using the constructor implicitly, so I prefer not touching it in this changeset at least. All the copies are deep, clarified now.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20404#discussion_r2352336557