On Mon, 8 Dec 2025 08:13:34 GMT, Christian Hagedorn <[email protected]> wrote:
> This patch turns the boolean flag `_flat_in_array` into a new `FlatInArray` > enum to properly define a (Boolean) lattice. This mainly allows us to cleanly > represent "maybe flat in array" and "not flat in array". The dedicated top > element is the dual of "maybe flat in array". > > To simplify the review and to better understand what the changes are, I added > code comments directly in the PR. > > Here is a high-level overview of the changes: > - `FlatInArray` enum to define a lattice for `flat_in_array`: > https://github.com/openjdk/valhalla/blob/6b1930c7b9a359223a998d0086a1326a9d7905e7/src/hotspot/share/opto/type.hpp#L1182-L1199 > - Updated `meet` operations accordingly. Needed to be careful when doing the > meet above the centerline. > - Added single `compute_flat_in_array()` method to properly compute the > `flat_in_array` property from the information we have when we need to set > flat in array newly (this was no properly done before). > - In `flatten_alias_type()`, we flatten to "maybe flat in array". > > #### Testing: > - t1-4 + valhalla-comp-stress > > Thanks for your feedback, > Christian This pull request has now been integrated. Changeset: a826fbd0 Author: Christian Hagedorn <[email protected]> URL: https://git.openjdk.org/valhalla/commit/a826fbd06ab41c483f59c06fed1757fae8c3a183 Stats: 530 lines in 11 files changed: 288 ins; 141 del; 101 mod 8332406: [lworld] C2: Turn flat in array property into proper lattice in type system to address remaining issues Reviewed-by: thartmann ------------- PR: https://git.openjdk.org/valhalla/pull/1774
