RFR: 8349374: [JVMCI] concurrent use of HotSpotSpeculationLog can crash [v2]

[Tom Rodriguez]

On Tue, 4 Feb 2025 19:36:36 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> I'm filtering out 0 above this line and `getFailedSpeculationsAddress()` can't return 0 if `failedSpeculationsAddress` is already non-zero.
>> 
>> `failedSpeculationsAddress` also can't be 0 if `managesFailedSpeculations` is false since we throw `IllegalArgumentException` in that case.
>
>> `failedSpeculationsAddress` also can't be 0 if `managesFailedSpeculations` is false since we throw `IllegalArgumentException` in that case.
> 
> Ok, I'd forgotten about that invariant. Might be worth reminding the reader of it with a comment in collectFailedSpeculations.

It's already the style in other places like the call to addFailedSpeculation so I'm not sure it's worth calling out here.  I've updated the javadoc for getFailedSpeculationsAddress to specify that it always returns non-zero.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23444#discussion_r1941877712