RFR: 8357822: C2: Multiple string optimization tests are no longer testing string concatenation optimizations [v2]

[Daniel Skantz]

On Thu, 5 Jun 2025 08:51:11 GMT, Daniel Skantz <dskantz at openjdk.org> wrote:

>> This PR updates a few tests to reintroduce testing of string concatenation optimizations since a few bugs have recently been identified in this area.
>> 
>> Selection criteria: performed a text search on the test suite and identified tests for string concatenations or string optimizations that are not currently compiled with `-XDstringConcat=inline` and are not using StringBuilders explicitly.
>> 
>> Testing: T1-4.
>> 
>> Extra testing: ran the tests manually with `-XX:+PrintOptimizeStringConcat` and verified that the tests are exercising string optimizations after the fix.
>
> Daniel Skantz has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - revert change to TestStringIntrinsics.java
>  - Update test/hotspot/jtreg/compiler/c2/Test7046096.java
>    
>    Co-authored-by: Emanuel Peter <emanuel.peter at oracle.com>

Thanks for the reviews and suggestions!

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PR Comment: https://git.openjdk.org/jdk/pull/25610#issuecomment-2954752738