The addition of the NULLABLE_NON_ATOMIC_FLAT layout forced the addition of a null-marker in all value classes instances, causing a instance size increase for value classes which didn't supported any nullable layout before. This size increase caused some performance regressions which boxing classes Double and Long. This patch temporarily disables the support for the NULLABLE_NON_ATOMIC_FLAT layout in classes Long and Double. A longer term solution will be developed and is tracked by JDK-8382361.
Tested on Mach5: tiers 1-4 Thanks to @dafedafe for measuring the performance with the fix. - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - Disable NULLABLE_NON_ATOMIC_FLAT layout for Double and Long Changes: https://git.openjdk.org/valhalla/pull/2331/files Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2331&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8379145 Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 mod Patch: https://git.openjdk.org/valhalla/pull/2331.diff Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2331/head:pull/2331 PR: https://git.openjdk.org/valhalla/pull/2331
