On Wed, 16 Sep 2026 11:35:14 GMT, Johan Sjölen <[email protected]> wrote:
>> The fields declaring layout support for value classes are duplicated across >> the FieldLayoutBuilder, InlineKlass, and ClassFileParser. I suggest that we >> move all of these into a new class, called AvailableLayouts. >> >> This rids us of many duplicated lines of code, and makes keeping the names >> consistent easier (today, they are not consistent). >> >> For the design of `AvailableLayouts`, I decided on putting the size fields >> into an array which is indexed by casting `LayoutKind` into an `int`. This >> saves us code bloat, both in the repo, and also in our binaries. When I've >> looked at the generated code for the inlined callsites of >> `InlineKlass::layout_size_in_bytes`, the switch is compiled down into table >> dispatch. Now, we can just have it be a load from an object offset. This >> ought to be faster as well, as no prediction needs to take place. >> >> There's a lot of added `const` stuff in this PR as well, as issues with >> const-correctness came up during the refactoring. >> >> --------- >> - [X] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > Johan Sjölen has updated the pull request incrementally with one additional > commit since the last revision: > > Service agent fixes src/hotspot/share/runtime/vmStructs.cpp line 227: > 225: nonstatic_field(InstanceKlass, _adr_value_klass_members, > address) \ > 226: nonstatic_field(ValueKlass::Members, > _available_layouts._payload_offset, int) > \ > 227: nonstatic_field(ValueKlass::Members, > _available_layouts._null_marker_offset, int) > \ SA should follow HotSpot structure as possible. It is better to add mirror class of `LayoutDescriptions` into SA, and it should be used. I think you can refer `ValueKlass::Members` to know how SA accesses internal fields. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/32276#discussion_r4033617375
