[jdk8u-dev] RFR: 8072422: Cleanup: Remove some unused flags/code in loop optimizations [v2]

[Severin Gehwolf]

On Fri, 25 Mar 2022 07:17:26 GMT, Yi Yang <yyang at openjdk.org> wrote:

>> We encountered this problem in downstream JDK. This is a backport of JDK-8283672, which simply removes several diagnostic flags, build passed. There is a related fix https://bugs.openjdk.java.net/browse/JDK-8159715, I would backport it after the current fix merged.
>> 
>> Original changeset: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/a1e41855499b
>> 
>> Please help review it.
>> 
>> Thanks.
>
> Yi Yang has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:
> 
>   8072422: Cleanup: Remove some unused flags/code in loop optimizations

> We do need the cleanup patch, because [alibaba/dragonwell8#305](https://github.com/alibaba/dragonwell8/issues/305) reports a crash due to use of UnrollLoopLimit, this flag is not supposed to be used by end users, it could be removed by cleanup patch. As I understand, the cleanup patch introduces another problem that can be fixed by JDK-8159715, so once cleanup backport is merged, I will backport JDK-8159715 as well.

So we have a work-around: Don't use `-XX:+UnlockDiagnosticVMOptions -XX:-UnrollLimitCheck`. We shouldn't take backporting non-critical fixes to JDK 8u lightly. This very much sounds like a `jdk8u-fix-no` candidate to me. Are you aware of this?  https://mail.openjdk.java.net/pipermail/jdk8u-dev/2020-June/012002.html

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PR: https://git.openjdk.java.net/jdk8u-dev/pull/22