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

[David Holmes]

On 12/01/2021 12:22 pm, David Holmes wrote:
> On 11/01/2021 7:59 pm, Thomas Stuefe wrote:
>> 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.
> 
> Sorry for the delay, I've emailed mobile-dev to see what their usage 
> state is.

But that aside I've just looked at the proposed RISC-V 64 port and they 
declare USE_LIBRARY_BASED_TLS_ONLY for JDK 11 at least (mainline port is 
not public yet). So perhaps it would be prudent to leave this in place 
for a while longer and just make the AIX specific change.

Cheers,
David

> Cheers,
> David
> 
>> Cheers, Thomas
>>
>> -------------
>>
>> PR: https://git.openjdk.java.net/jdk/pull/1976
>>