P4
Sub-classes of InstanceKlass can't have C++ fields because they would end up overlayed on top of the vtable and other dynamically sized sections of the InstanceKlass object.
To handle that the InlineKlass has a companion class named InlineKlassFixedBlock, which lists all the member fields that belongs to the InlineKlass, and an instance of that gets stamped into the InlineKlass object after the parts that are provided by the InstanceKlass.
This Enhancement suggests a couple of changes:
1) Move InlineKlassFixedBlock away from instanceKlass.hpp and place it inside inlineKlass.hpp instead.
2) Nest InlineKlassFixedBlock it inside InlineKlass. It's only InlineKlass (and the compilers) that touch these fields, so it doesn't have to be a public, top-level class.
3) Rename it from InlineKlassFixedBlock to InlineKlass::Members. I think that "fixed block" term is unclear and doesn't help the reader understand its role in the InlineKlass. Hopefully, Members is a clearer name.
To handle that the InlineKlass has a companion class named InlineKlassFixedBlock, which lists all the member fields that belongs to the InlineKlass, and an instance of that gets stamped into the InlineKlass object after the parts that are provided by the InstanceKlass.
This Enhancement suggests a couple of changes:
1) Move InlineKlassFixedBlock away from instanceKlass.hpp and place it inside inlineKlass.hpp instead.
2) Nest InlineKlassFixedBlock it inside InlineKlass. It's only InlineKlass (and the compilers) that touch these fields, so it doesn't have to be a public, top-level class.
3) Rename it from InlineKlassFixedBlock to InlineKlass::Members. I think that "fixed block" term is unclear and doesn't help the reader understand its role in the InlineKlass. Hopefully, Members is a clearer name.
- links to
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Commit(lworld)
openjdk/valhalla/d586e57d
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Review(lworld)
openjdk/valhalla/1812