RFR: Small fixes - shipment one

[Coleen Phillimore]

On Tue, 22 Mar 2022 15:26:14 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> src/hotspot/share/runtime/continuation.cpp line 1213:
>> 
>>> 1211: 
>>> 1212:       chunk = allocate_chunk(cont_size + ContinuationHelper::frame_metadata);
>>> 1213:       if (UNLIKELY(chunk == nullptr || !_thread->cont_fastpath() || _barriers)) { // OOME/probably humongous
>> 
>> This is just a strange set of conditions.  Why would you allocate_chunk if  _thread->cont_fastpath() is false? or _barriers, whatever that means.  Really don't expect a function like allocate_chunk to have side effects.
>> Maybe in the latter two conditions, you still want to zero out the chunk in the tail and don't want to remove this.
>
> The variable _barriers is set by allocate_chunk, so it must be check afterwards.
> If allocation safepoints and there is JVM TI qeury it can 'remove' us as available for fastpath.
> If allocation fails due to OOME.
> 
> The init_chunk() should always zero enought.

Ok, thanks for confirming that it's already zeroed.

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PR: https://git.openjdk.java.net/loom/pull/114