> Improve the speed of Enum.hashCode by caching the identity hashcode on first > use. I've seen an application where Enum.hashCode is a hot path, and this is > fairly simple speedup. The memory overhead is low; in enums with no extra > fields there is already a 4-byte space due to alignment so this new field can > slot in 'for free'. In other cases, the singleton nature of enum values means > that the number of total instances is typically very low, so a small > per-instance overhead is not a concern. > > Please see more discussion/explanation in the [original enhancement > request](https://bugs.openjdk.org/browse/JDK-8306075). [Benchmark results and > generated code analysis moved to comment] > > Thanks @shipilev for help with the implementation and interpreting the > generated code.
olivergillespie has updated the pull request incrementally with one additional commit since the last revision: Switch to non-javadoc comment and remove markup ------------- Changes: - all: https://git.openjdk.org/jdk/pull/13491/files - new: https://git.openjdk.org/jdk/pull/13491/files/79af4952..f4b5c546 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=13491&range=04 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13491&range=03-04 Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod Patch: https://git.openjdk.org/jdk/pull/13491.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/13491/head:pull/13491 PR: https://git.openjdk.org/jdk/pull/13491
