RFR: 8306842: Classfile API performance improvements [v7]

[Chen Liang]

On Tue, 16 May 2023 14:23:04 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> Adam Sotona has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   LinkedList replaced with ArrayList in benchmarks
>
> src/java.base/share/classes/jdk/internal/classfile/impl/StackMapDecoder.java line 83:
> 
>> 81:             vtis = new VerificationTypeInfo[methodType.parameterCount()];
>> 82:         }
>> 83:         for(var arg : methodType.parameterList()) {
> 
> `MethodTypeDesc::parameterList` copies the internal `ClassDesc[]`, so desugaring loop from `0` to `mdesc.parameterCount()` might be a small improvement for this and a few other cases.

I plan to share a backing list in #13186, with API additions so users can avoid copying their input immutable parameter list as well. I see no reason to use a direct array, for MTD is not passed to and used by the VM, unlike MethodType.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13671#discussion_r1195328671