RFR: JDK-8316991: Reduce nullable allocation merges [v8]

[Vladimir Kozlov]

On Thu, 21 Mar 2024 22:02:54 GMT, Cesar Soares Lucas <cslucas at openjdk.org> wrote:

>> Cesar Soares Lucas has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:
>> 
>>  - Catching up with master
>>  - Fix broken build.
>>  - Merge with origin/master
>>  - Update test/micro/org/openjdk/bench/vm/compiler/AllocationMerges.java
>>    
>>    Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>
>>  - Ammend previous fix & add repro tests.
>>  - Fix to prevent reducing already reduced Phi
>>  - Fix to prevent creating NULL ConNKlass constants.
>>  - Refrain from RAM of arrays and Phis controlled by Loop nodes.
>>  - Fix typo in test.
>>  - Fix build after merge.
>>  - ... and 2 more: https://git.openjdk.org/jdk/compare/7231fd78...620f9da8
>
> @vnkozlov @TobiHartmann - Can you please run your tests again on this if that's not too much to ask?
> 
> Can someone please take a look at these changes? /cc @iwanowww

@JohnTortugo I thought you will also enable `ReduceAllocationMerges` by default.

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PR Comment: https://git.openjdk.org/jdk/pull/15825#issuecomment-2013991787