On Fri, 28 Aug 2026 03:47:02 GMT, Ioi Lam <[email protected]> wrote: > `FieldClosure` is used for iterating fields in an object. For Valhalla, it > has been enhanced to handle fields that are inside inlined fields. However, > the current implementation has two problems: > > [1] It type casts the address of an inlined field into an `oop` pointer. This > is unsafe as many operations, such as getting the header of an `oop`, will > not work with such an `oop` pointer: > > https://github.com/openjdk/jdk/blob/b1f975efa481bd5e20c1b7d58a87d0866df205e6/src/hotspot/share/runtime/fieldDescriptor.cpp#L216 > > [2] The parameter `base_offset` is used in many functions. Its meaning is > unclear and inconsistent. > > https://github.com/openjdk/jdk/blob/b1f975efa481bd5e20c1b7d58a87d0866df205e6/src/hotspot/share/runtime/fieldDescriptor.cpp#L159 > > https://github.com/openjdk/jdk/blob/b1f975efa481bd5e20c1b7d58a87d0866df205e6/src/hotspot/share/oops/instanceKlass.hpp#L99-L101 > > This RFE refactors `FieldClosure` to avoid the above problems. `FieldClosure` > now carries information about inlined fields. This information can be used by > various field iteration code to simplify their operations. See > `FieldClosure::inline_klass()` and `FieldClosure::inline_offset()`. > > As a result, users of `FieldClosure` and `FieldDescriptor()` no longer need > to perform obscure arithmetics with `InlineKlass::payload_offset()`. > > This RFE also moves a few common operations into utility functions to avoid > code duplication. > > Also: > - Fixed a bug in `FlatArrayKlass::oop_print_elements_on()` in the handling of > nullable elements. > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai).
src/hotspot/share/cds/heapShared.cpp line 1784: > 1782: } > 1783: > 1784: // Recursively scan for any InlineKlass K that has least one non-null > inlined instance We've tried to standardize the terminology by using "flat" everywhere -> flat field, flat array, etc. Before that, we had too many variations: flat, flatten, flattened, inline, inlined, etc. We might have missed some spots, but this renaming is going against this effort. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/32565#discussion_r3925036646
