On Fri, 15 May 2026 13:04:02 GMT, Manuel Hässig <[email protected]> wrote:
> This PR updates the Test `compiler/stable/TestStableArrayMembars.java` for > Valhalla. This involves creating a code path for migrated value classes and a > slight change to C2 to be able to clean up more barriers than previously. > > Unfortunately, with `--enable-preview` C2 is not able to fully clean up all > membars as it is for mainline. This is due to the later elision of the loads. > After parsing, membars do not carry information that could relate them to any > particular memory access, so we cannot remove them without potentially > violating the JMM. Further, the implementation of > `Unsafe.getFlatValueAcquire` emits a barrier in Java that cannot be > eliminated by the JIT anyways. > > Testing: > - [x] tier1,tier2 and additional stress testing. > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). Looks good to me. test/hotspot/jtreg/compiler/stable/TestStableArrayMembars.java line 134: > 132: IRNode.LOAD, "=1"}, // There is exactly one load > fence, but no load > 133: applyIfAnd = {"enable-valhalla", "true", > 134: "UseArrayFlattening", "true"}) Suggestion: "UseArrayFlattening", "true"}) ------------- Marked as reviewed by thartmann (Committer). PR Review: https://git.openjdk.org/valhalla/pull/2441#pullrequestreview-4317438898 PR Review Comment: https://git.openjdk.org/valhalla/pull/2441#discussion_r3265027839
