[jdk25u] RFR: 8370049: [s390x] G1 barrier compareAndExchange does not return old value when compareExchange fails

[duke]

On Tue, 21 Oct 2025 19:01:04 GMT, Vladimir Petko <vpetko at openjdk.org> wrote:

> Backporting JDK-8370049 to avoid hard-to-diagnose synchronisation issues on S390x. 
> 
> S390x tests:
> 
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR  SKIP   
>    jtreg:test/hotspot/jtreg/compiler/gcbarriers/TestG1BarrierGeneration.java
>                                                          1     1     0     0     0   
> ==============================
> TEST SUCCESS
> 
> 
> Tier1:
> 
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR  SKIP   
>    jtreg:test/hotspot/jtreg:tier1                     3027  2383     0     0   644   
>>> jtreg:test/jdk:tier1                               2527  2421     2     0   104 <<
>    jtreg:test/langtools:tier1                         4654  4645     0     0     9   
>    jtreg:test/jaxp:tier1                                 0     0     0     0     0   
>    jtreg:test/lib-test:tier1                            37    37     0     0     0   
> ==============================
> TEST FAILURE
> 
> Unrelated failure:
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR  SKIP   
>    jtreg:test/jdk/java/lang/ProcessBuilder/Basic.java
>>>                                                       2     0     2     0     0 <<
> ==============================
> TEST FAILURE
> 
> It will be addressed by https://github.com/openjdk/jdk25u/pull/334
> 
> 
> Tier2 tests:
> 
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR  SKIP   
>>> jtreg:test/hotspot/jtreg:tier2                      946   755     1     0   190 <<
>>> jtreg:test/jdk:tier2                               4319  4076     3     0   240 <<
>    jtreg:test/langtools:tier2                           14    12     0     0     2   
>    jtreg:test/jaxp:tier2                               517   516     0     0     1   
>    jtreg:test/docs:tier2                                 4     0     0     0     4   
> ==============================
> TEST FAILURE
> 
> 
> 
> Unrelated failures:
> 1. applications/ctw/modules/jdk_jfr.java                                                      Failed. Execution failed: `main' threw exception: java.lang.AssertionError: There were 1 errors:[{modules_jdk_jfr_0: failed during compilation of class ... jdk/jfr/internal/jfc/JFC}] ...

@vpa1977 
Your change (at version c153e695fdcb1423672a4631eddb7ca07e9952e4) is now ready to be sponsored by a Committer.

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PR Comment: https://git.openjdk.org/jdk25u/pull/330#issuecomment-3438691885