RFR: 8288497: add support for JavaThread::is_oop_safe() [v3]

[David Holmes]

On Fri, 17 Jun 2022 15:21:01 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> A fix to add support for JavaThread::is_gc_barrier_detached() which allows
>> us to add checks to detect failures like:
>> 
>>     JDK-8288139 JavaThread touches oop after GC barrier is detached
>>     https://bugs.openjdk.org/browse/JDK-8288139
>> 
>> This fix along with the fix for JDK-8288139 has been tested in Mach5 Tier[1-8].
>> There are no related failures in Mach5 Tier[1-7]; Mach5 Tier8 is still running.
>
> Daniel D. Daugherty has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Rename cannot_access_oops_safely to is_oop_safe and invert the function's logic.

Thanks for the updates Dan and your patience.

One minor query/suggestion below, but this is good as-is.

Thanks.

src/hotspot/share/runtime/thread.inline.hpp line 269:

> 267: }
> 268: 
> 269: inline bool JavaThread::is_oop_safe() const {

Do we want to document, and assert, that this is only intended for use by the current thread on itself? I can't imagine any scenario where we would need to ask whether an arbitrary thread is oop-safe. ??

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.org/jdk19/pull/20