RFR: 8332249: Micro-optimize Method.hashCode [v2]

[Chen Liang]

On Thu, 6 Jun 2024 06:41:48 GMT, ExE Boss <duke at openjdk.org> wrote:

>> Sean Gwizdak has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
>> 
>>  - Remove trailing whitespace.
>>  - Move hashCode benchmark into the newly created MethodBenchmark file
>>  - Merge branch 'master' into method-hashcode-JDK-8332249
>>  - Remove changes to JavaDoc per guidance.
>>  - Fix whitespace issues pointed by the bot
>>  - Micro-optimize Method.hashCode
>
> src/java.base/share/classes/java/lang/reflect/Method.java line 392:
> 
>> 390:                 .hashCode();
>> 391:         }
>> 392:         return hc;
> 
> The `hash` field should probably somehow be shared with the `Method.root` instance, so that it doesn’t need to be recomputed when different code gets a `Method` reference.

Currently the hashCode computation is quite cheap. I think we can consider this delegation if it gets more complex, say if the hash code now considers parameters.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/19433#discussion_r1629365372