RFR: 8338546: Speed up ConstantPoolBuilder::classEntry(ClassDesc) [v2]

[Chen Liang]

On Thu, 22 Aug 2024 13:45:31 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:
>> 
>>  - Improve benchmark as suggested
>>  - Merge branch 'master' of https://github.com/openjdk/jdk into feature/classentry-speedup
>>  - Fix microbenchmark
>>  - Improve jmh
>>  - 8338546: Speed up ConstantPoolBuilder::classEntry(ClassDesc)
>
> src/java.base/share/classes/jdk/internal/classfile/impl/Util.java line 372:
> 
>> 370:      * }
>> 371:      * }
>> 372:      * This is converted to explicit initialization to avoid bootstrap overhead.
> 
> Have you measured this to be true and useful? Static array initializers are bulky at a bytecode level so sometimes just generating on the fly carries insignicant overhead. Then the `UtilTest` assertion test wouldn't really be needed.

I measured in bytestacks and the clinit instructions reduced by about 2/3

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PR Review Comment: https://git.openjdk.org/jdk/pull/20667#discussion_r1760046569