RFR: 8295214: Generational ZGC: Guard nmethods from cross modifying code

[Erik Österlund]

On Wed, 9 Nov 2022 10:13:55 GMT, Erik Österlund <eosterlund at openjdk.org> wrote:

>> src/hotspot/share/runtime/safepointMechanism.cpp line 144:
>> 
>>> 142: 
>>> 143:   update_poll_values(thread);
>>> 144:   OrderAccess::cross_modify_fence();
>> 
>> Has this simply been moved to cover more paths?
>
> The new logic inside of update_poll_values makes is more accurate and made this cross_modify_fence redundant. That's why I removed it.

> Has this simply been moved to cover more paths?

I removed it because it is redundant after updating update_poll_values to more precisely identify when cross_modify_fence should be called. It will then already have been called inside of update_poll_values, when it was needed here at the call site.

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PR: https://git.openjdk.org/jdk/pull/11042