RFR: JDK-8259372: remove AIX related USE_LIBRARY_BASED_TLS_ONLY and THREAD_LOCAL special handling

[Thomas Stuefe]

On Thu, 7 Jan 2021 22:42:02 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> AIX 5.3 had buggy __thread support (see JDK-8176442).
>> That's why we introduced a macro USE_LIBRARY_BASED_TLS_ONLY and set it only to 1 on AIX (different to the other platforms supported by the OpenJDK).
>> However AIX 5.3 support was removed some time ago (currently we have a minimum requirement of AIX 7.X ) so the whole USE_LIBRARY_BASED_TLS_ONLY related coding could be removed.
>
> Hi Matthias,
> We didn't introduce USE_LIBRARY_BASED_TLS_ONLY just for AIX, it was also added to aid the mobile project:
> http://mail.openjdk.java.net/pipermail/hotspot-dev/2015-November/020765.html
> Before removing it we would need to have a broader discussion.
> Thanks,
> David

Hi Matthias,

Removal looks good. I have a small preference for leaving it in; but OTOS we never really test this coding since all main platforms use __thread. Maybe removal is good then. I'll defer to David for the final decision.

Cheers, Thomas

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PR: https://git.openjdk.java.net/jdk/pull/1976