On Wed, 8 Mar 2023 16:05:57 GMT, Coleen Phillimore <cole...@openjdk.org> wrote:
>> Please review this change re-implementing the FieldInfo data structure. >> >> The FieldInfo array is an old data structure storing fields metadata. It has >> poor extension capabilities, a complex management code because of lack of >> strong typing and semantic overloading, and a poor memory efficiency. >> >> The new implementation uses a compressed stream to store those metadata, >> achieving better memory density and providing flexible extensibility, while >> exposing a strongly typed set of data when uncompressed. The stream is >> compressed using the unsigned5 encoding, which alreay present in the JDK >> (because of pack200) and the JVM (because JIT compulers use it to comrpess >> debugging information). >> >> More technical details are available in the CR: >> https://bugs.openjdk.org/browse/JDK-8292818 >> >> Those changes include a re-organisation of fields' flags, splitting the >> previous heterogeneous AccessFlags field into three distincts flag >> categories: immutable flags from the class file, immutable fields defined by >> the JVM, and finally mutable flags defined by the JVM. >> >> The SA, CI, and JVMCI, which all used to access the old FieldInfo array, >> have been updated too to deal with the new FieldInfo format. >> >> Tested with mach5, tier 1 to 7. >> >> Thank you. > > src/hotspot/share/classfile/fieldLayoutBuilder.cpp line 554: > >> 552: FieldInfo ctrl = _field_info->at(0); >> 553: FieldGroup* group = nullptr; >> 554: FieldInfo tfi = *it; > > What's the 't' in tfi? Maybe a longer variable name would be helpful here. At some point there was a TempFieldInfo type, hence the name. Renamed to fieldinfo. > src/hotspot/share/classfile/javaClasses.cpp line 871: > >> 869: // a new UNSIGNED5 stream, and substitute it to the old FieldInfo >> stream. >> 870: >> 871: int java_fields; > > Can you put InstanceKlass* ik = InstanceKlass::cast(k); here and use that so > there's only one cast? Sure, done. ------------- PR: https://git.openjdk.org/jdk/pull/12855
