RFR: 8282322: AArch64: Provide a means to eliminate all STREX family of instructions [v3]

[Dmitry Chuyko]

On Tue, 24 May 2022 06:54:59 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Dmitry Chuyko has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
>> 
>>  - Merge branch 'openjdk:master' into JDK-8282322
>>  - Use LSE in linux-aarch64 asm code if __ARM_FEATURE_ATOMICS is on
>>  - Revert "hardlse feature"
>>    
>>    This reverts commit c5da85d3282bb995f69639f8f592cc94560916c5.
>>  - Merge branch 'openjdk:master' into JDK-8282322
>>  - hardlse feature
>
> src/hotspot/cpu/aarch64/vm_version_aarch64.cpp line 257:
> 
>> 255: // Forcibly enable runtime LSE support
>> 256:   FLAG_SET_DEFAULT(UseLSE, true);
>> 257: #else
> 
> I don't believe this block does anything useful, and it disables `-XX:-UseLSE` for testing.

Agree, I restored original detection code (it just does what we need on the right hardware).

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PR: https://git.openjdk.java.net/jdk/pull/8779