RFR: 6983726: remove Proxy from MethodHandleProxies.asInterfaceInstance SAM conversion [v4]

[Chen Liang]

On Wed, 5 Apr 2023 13:22:30 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Chen Liang 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 13 additional commits since the last revision:
>> 
>>  - Use a dumper for interface instances, other cleanup
>>  - Merge branch 'master' into explore/mhp-iface
>>  - Merge branch 'master' into explore/mhp-iface
>>  - Remove unused JavaLangReflectReflectAccess.invokeDefault
>>  - rethrow error
>>  - Benchmark compareing to lamda metafactory, various minor updates
>>  - Cache the spinned class, loading is still slow
>>  - Wrapper instance type is already available
>>  - mark records as private
>>  - Merge branch 'master' into explore/mhp-iface
>>  - ... and 3 more: https://git.openjdk.org/jdk/compare/118045b8...0eec507d
>
> src/java.base/share/classes/java/lang/invoke/MethodHandleProxies.java line 213:
> 
>> 211:                     .defineClassAsLookup(true, List.of(mhs));
>> 212:             proxy = lookup.findConstructor(lookup.lookupClass(), methodType(void.class))
>> 213:                     .asType(methodType(Object.class)).invokeExact();
> 
> This can use `invoke` instead of an explicit `asType` and `invokeExact`. It is more or less the same.
> Suggestion:
> 
>             proxy = lookup.findConstructor(lookup.lookupClass(), methodType(void.class)).invoke();

Fyi the original code was an emulation of how LambdaMetafactory initializes no-arg lambda instances.

> src/java.base/share/classes/java/lang/invoke/MethodHandleProxies.java line 225:
> 
>> 223:     private record LocalMethodInfo(MethodTypeDesc desc, List<ClassDesc> thrown) {}
>> 224: 
>> 225:     private record InterfaceInfo(@Stable MethodType[] types, Lookup lookup, @Stable byte[] template) {}
> 
> Use of `@Stable` here is not needed. We don't constant fold through `InterfaceInfo` instances.
> Suggestion:
> 
>     private record InterfaceInfo(MethodType[] types, Lookup lookup, byte[] template) {}

Hmm, I thought records are constant-folded. https://github.com/openjdk/jdk/blob/44f33ad1a9617fc23864c9ba5f063b3fc2f1e18c/src/hotspot/share/ci/ciField.cpp#L240 Per https://github.com/openjdk/jdk/pull/9143#discussion_r912239501, array cloning sees 10% less time per operation with the annotation.

I will try with and without these annotations and report the creation benchmark results to see if they are worth it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13197#discussion_r1158852847
PR Review Comment: https://git.openjdk.org/jdk/pull/13197#discussion_r1158872512