On Mon, 27 Apr 2026 14:28:27 GMT, Joel Sikström <[email protected]> wrote:
> Hello, > > Embdedded flat contended fields might not be included in the class' OopMap if > there are no other oop fields in the holder class. > > Flat fields are handled separately in fieldLayoutBuilder.cpp, resulting in > the current `_oop_count` not being updated if a flat field contains oops. > This is OK, since the oop fields are handled at a later point in time. > However, for contended fields, which are part of the contended group, > embedded oop fields are only tracked if: `cg->oop_count() > 0`, which is not > guaranteed to be true. > > I've written a test to see if the oop field is included in the class' OopMap > and also changed the `_oop_count` field `_has_embedded_oops`, and changed > that to a boolean property, which is how we've used it so far. > > Since embedded fields in flat paylods are not tracked in `cg->oop_fields()`, > we can't do the assert that is currently there, so I just removed that. > > Testing: > * New test fails without the fixes in fieldLayoutBuilder and passes with fixes > * Running Oracle's tier1-3 > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). This pull request has now been integrated. Changeset: 301fe4a9 Author: Joel Sikström <[email protected]> URL: https://git.openjdk.org/valhalla/commit/301fe4a997ba11211079661cce174d8fd3460858 Stats: 95 lines in 3 files changed: 83 ins; 8 del; 4 mod 8383415: [lworld] Flat contended oop field might not be included in OopMap Reviewed-by: fparain, aboldtch, phubner ------------- PR: https://git.openjdk.org/valhalla/pull/2371
