On Fri, 3 Jul 2026 12:38:04 GMT, Christian Hagedorn <[email protected]> wrote:
> The `clone()` intrinsic directly returns a value object because it has no > identity - the clone is trivially a no-op: > https://github.com/openjdk/valhalla/blob/2af7c2350b22ed03850b6b6c146b622ca758f441/src/hotspot/share/opto/library_call.cpp#L6041-L6045 > > But this is incorrect if the value class does not implement `Cloneable`. In > this case, we must throw `CloneNotSupportedException` which is currently > missing. > > The fix adds a check whether the value class implements `Cloneable`. If it > does, we execute the existing code no-op path. Otherwise, we could either do > a call to the runtime `clone()` implementation, as done for the existing slow > path of this intrinsic, or we simply emit an uncommon trap. I've decided to > use the latter approach since it's more straight forward and rather an > edge-case situation. I also included a `too_many_traps()` check to avoid > repeated recompilations. > > Thanks, > Christian > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). Thanks Tobias for your review! I've added some more tests to exercise the cases when we don't know that we are dealing with a value object during parsing: - `testCloneAbstract`: We never know that it is a value object. - `testCloneAbstractRef/Val`: We only know after parsing that we have a ref or value object. ------------- PR Comment: https://git.openjdk.org/valhalla/pull/2625#issuecomment-4877066603
