RFR: 8348853: Fold layout helper check for objects implementing non-array interfaces

Marc Chevalier mchevalier at openjdk.org
Wed Mar 26 10:14:19 UTC 2025


If `TypeInstKlassPtr` represents an array type, it has to be `java.lang.Object`. From contraposition, if it is not `java.lang.Object`, we can conclude it is not an array, and we can skip some array checks, for instance.

In this PR, we improve this deduction with an interface base reasoning: arrays implements only Cloneable and Serializable, so if a type implements anything else, it cannot be an array.

This change partially reverts the changes from [JDK-8348631](https://bugs.openjdk.org/browse/JDK-8348631) (#23331) (in `LibraryCallKit::generate_array_guard_common`) and the test still passes.

The way interfaces are check might be done differently. The current situation is a balance between visibility (not to leak too much things explicitly private), having not overly general methods for one use-case and avoiding too concrete (and brittle) interfaces.

Tested with tier1..3, hs-precheckin-comp and hs-comp-stress

Thanks,
Marc

-------------

Commit messages:
 - Revert now useless fix
 - Generalize the not-array proof

Changes: https://git.openjdk.org/jdk/pull/24245/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24245&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348853
  Stats: 46 lines in 5 files changed: 35 ins; 7 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/24245.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24245/head:pull/24245

PR: https://git.openjdk.org/jdk/pull/24245


More information about the graal-dev mailing list