RFR: 8303210: [linux, Windows] Make UseSystemMemoryBarrier available as product flag [v5]

[David Holmes]

On Wed, 29 Mar 2023 10:30:45 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> src/hotspot/os/aix/os_aix.cpp line 2348:
>> 
>>> 2346:     }
>>> 2347:     FLAG_SET_ERGO(UseSystemMemoryBarrier, false);
>>> 2348:   }
>> 
>> This looks like a leftover ?? It shouldn't be here.
>
> Thanks! The one above in os::init was the leftover. The flags are initialized in `init_2`.

But this code isn't callling `SystemMemoryBarrier::initialize` ??

Ah now I see - this is a hard-coded "flag not supported". But there is no need to do that as `SystemMemoryBarrier::initialize` tells you whether it is supported or not.

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PR Review Comment: https://git.openjdk.org/jdk/pull/12753#discussion_r1152619465