On Tue, 19 May 2026 14:34:57 GMT, Tobias Hartmann <[email protected]> wrote:
> C1/interpreter array-access profiling is racy and can publish the exact array > klass before the flat/null-free flag is visible: > https://github.com/openjdk/valhalla/blob/f87d6d1cea3b578b458075a411f7aaa5dddb2cd9/src/hotspot/share/c1/c1_LIRGenerator.cpp#L1968-L1971 > > C2 reads profile information lock-free and can therefore, in rare cases, > observe the inconsistencies reported in the JBS issue. For example, it can > observe profiling for an array load with an `array_type` that is knowingly > flat but does not have the `flat_array` property set (yet). The new > regression test reliably reproduces such inconsistencies for array loads and > stores. > > Since a valid profiled flat array klass is stronger information than the flat > flag, the fix is to prefer that information if available. With that fix, the > asserts don't make much sense anymore, so I removed them. > > Thanks, > Tobias > > --------- > - [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: c5fafa9b Author: Tobias Hartmann <[email protected]> URL: https://git.openjdk.org/valhalla/commit/c5fafa9b6a2ee5410f92a3681876bc17d080769e Stats: 192 lines in 2 files changed: 176 ins; 15 del; 1 mod 8381373: [lworld] C2 failed assert(!flat || flat_array) failed: inconsistency Reviewed-by: qamai, dlong ------------- PR: https://git.openjdk.org/valhalla/pull/2452
