RFR: 8263125: During deoptimization vectors should reassign scalarized payload after all objects are reallocated. [v2]

[Richard Reingruber]

On Fri, 12 Mar 2021 16:58:18 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>>> And can't the payload for deoptimization be represented as a scalarized array in that case too? Maybe not because of the special handling a VectorMask requires.
>> 
>> Vector is special in a very similar way: debug info contains only vector value location. Custom logic is needed to turn it into scalarized array representation. And then there's still a step required to allocate the corresponding typed vector box which wraps the payload.
>> 
>> I'm not saying it is not possible to represent current on-heap shape solely in debug info, but it would require significant refactorings/enhancements of existing machinery. And would complicate possible changes of the on-heap vector/mask shape. It is not something "cut in stone" and can evolve over time.
>
>> > And can't the payload for deoptimization be represented as a scalarized array in that case too? Maybe not because of the special handling a VectorMask requires.
>> 
>> Vector is special in a very similar way: debug info contains only vector value location. Custom logic is needed to turn it into scalarized array representation. And then there's still a step required to allocate the corresponding typed vector box which wraps the payload.
>> 
>> I'm not saying it is not possible to represent current on-heap shape solely in debug info, but it would require significant refactorings/enhancements of existing machinery. And would complicate possible changes of the on-heap vector/mask shape. It is not something "cut in stone" and can evolve over time.
> 
> Yes, I said it too. It can be done but code would be much larger and more complicated.
> And, as Vladimir I. correctly pointed, VectorAPI is new code which can be evolved. To have specialized code for it makes it easy to do experiments.
> 
> Thank you @iwanowww and @reinrich for reviews.

I see. Thanks for elaborating on my question!

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PR: https://git.openjdk.java.net/jdk/pull/2924