> Currently, the hotspot compiler (as in ciField) trusts final fields in hidden > classes, record classes, and selected jdk packages. Some classes in the JDK > wish to be trusted, but they cannot apply package-wide opt-in due to other > legacy classes in the package, such as java.util. > > They currently can use `@Stable` as a workaround, but this is fragile because > a stable final field may hold a trusted null, zero, or false value, which is > currently treated as non-constant by ciField. > > We should add an annotation to opt-in for a whole class, mainly for legacy > packages. This would benefit greatly some of our classes already using a lot > of Stable, such as java.util.Optional, whose empty instance is now > constant-foldable, as demonstrated in a new IR test. > > Paging @minborg who requested Optional folding for review. > > I think we can remove redundant Stable in a few other java.util classes after > this patch is integrated. I plan to do that in subsequent patches.
Chen Liang has updated the pull request incrementally with one additional commit since the last revision: Move the test to a core library purposed directory ------------- Changes: - all: https://git.openjdk.org/jdk/pull/28540/files - new: https://git.openjdk.org/jdk/pull/28540/files/567e8925..16db9901 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=28540&range=06 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28540&range=05-06 Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod Patch: https://git.openjdk.org/jdk/pull/28540.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/28540/head:pull/28540 PR: https://git.openjdk.org/jdk/pull/28540
