On Fri, 6 Sep 2024 16:20:52 GMT, Coleen Phillimore <cole...@openjdk.org> wrote:
>> This change stores InstanceKlass for interface and abstract classes in the >> non-class metaspace, since class metaspace will have limits on number of >> classes that can be represented when Lilliput changes go in. Classes that >> have no instances created for them don't require compressed class pointers. >> The generated LambdaForm classes are also AllStatic, and changing them to >> abstract moves them to non-class metaspace too. It's not technically great >> to make them abstract and not final but you can't have both. Java classfile >> access flags have no way of specifying something like AllStatic. >> >> Tested with tier1-8. > > Coleen Phillimore has updated the pull request incrementally with one > additional commit since the last revision: > > Replace Metaspace::is_compressed_klass_ptr with > CompressedKlassPointers::is_in_encoding_range. On 9/10/24 12:42, Coleen Phillimore wrote: > Thanks for reviewing Ioi and Thomas, and thank you Thomas for the suggested > changes. I'm a bit concerned about this one. I'm working on megamorphic dispatch, and a uniform representation of compressed class pointers allows me to squeeze klass+offset into a single 64-bit word. This in turn allows fast and simple method lookups. I need, at least, to be able to use compressed interface pointers. If interfaces are "somewhere else", and thus incompressible, I can't do what I need to do. If, however, klass and non-klass metaspaces are contiguous I guess it'd be OK, if not ideal. I'd much rather use compressed klass pointers without having to decode them. All I need is a way to represent interface pointers in a compact way in lookup tables, and to be able to get from compressed class pointers to the address. As long as interface pointers are in a 32-bit range and there's a fast way to get from compressed class to address that's OK. -- Andrew Haley (he/him) Java Platform Lead Engineer Red Hat UK Ltd. <https://www.redhat.com> https://keybase.io/andrewhaley EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671 ------------- PR Comment: https://git.openjdk.org/jdk/pull/19157#issuecomment-2399545521
