RFR: 8353273: Reduce number of oop map entries in instances

[Thomas Stuefe]

On Tue, 1 Apr 2025 17:34:28 GMT, Frederic Parain <fparain at openjdk.org> wrote:

> A possible improvement to this code would be to compute if the super class' layout ends with oops during the reconstruction (reconstruct_layout()), to avoid having to iterate over the fields a second time.

That is a good idea. A prior version of this stored the last field information after constructing the layout in the InstanceKlass (as a "ends_with_oop" bool) but I did not like that, since I did not wanted to add a new member to IK. But if we reconstruct the layout for the super class anyway, I can do the same there. Thansk!

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PR Comment: https://git.openjdk.org/jdk/pull/24330#issuecomment-2770285950